Many people will tell you that on this day the Earth, Sun and the galactic center will come in one straight line and this alignment will have catastrophic effects. If you look at the star charts for 21st December 2012, you will realize, that its true! The Earth, Sun and the center of our galaxy will indeed come in one straight line. However, what they do not tell you is that this happens on every December 21st!! We have gloriously ‘survived’ all previous such instances.

There are other claims of a gigantic solar flare, geo magnetic pole reversal and collision with a mysterious planet X that are also making the rounds. Again, all these are baseless. Yes, the solar activity will peak in late 2011 or mid 2012, but the Sun does this every 11 years. The solar activity increases, drops to a minimum and peaks again in what is referred to as the solar cycle which has an 11 year period.

Geo magnetic pole reversals have happened in the distant past but it takes hundreds of years for the poles to reverse. Its a slow and gradual process and there will be many indications of this years before it happens. Scientist have no evidence about this so far. Similar is the story of planet X. If it were heading towards Earth, we would have seen perturbations in the orbits of other solar system objects. There is no evidence to support this what so ever.

So what about the Mayan calendar ending? The Mayans had a system which we refer to as the Long Count. They used it to keep track of historic dates. It served the same purpose as our calendar. It seems that the Long Count ends on the modern date of 21st December 2012. So what after that? Well, what happens after our calendar ends every year on 31st December. We start a new year. In much the same way a new Long Count will begin! It will bring in the first day of the next Long Count calendar or 22nd December 2012 for us. The world will survive to fight another such prophecy.

In my recent interactions with some students, I realized that black holes get portrayed in extremely bad light. They are made out to be the villains of the universe, angry and monstrous eating away anything they can find, may it be stars or sometimes even galaxies! I wondered where this notion comes from among the students. Then I realized its in the way black holes are described. These are objects that have the most intense gravity we know of. In fact their gravity is so strong that nothing, not even light can escape from them. Everything gets sucked into them and can never escape out.

As much as the first two statements describing these mysterious objects are correct, the third is quite misleading and it is this statement that creates confusion amongst the general public. If everything gets sucked into a black hole, how are we still here?

“Because we are not close to one of course!”

Ah! So how close does one have to be? What if for some odd reason the Sun shrinks in size and becomes a black hole right now? Will the Earth get sucked into it? Let us explore the situation that this will create.

Remember that this is a hypothetical situation. As far as we know the Sun will never reach this stage because it does not have sufficient mass. Only extremely massive stars become black holes at the end stages of their lives. This happens when all the hydrogen and other elements that they burn as fuel are exhausted. The outer layers of such stars blow up and the remaining mass is enough to accumulate together and form a black hole.

Scientists currently estimate that the Sun does not have this necessary mass. But let us ignore that fact and imagine that this actually happening. I am sure some of you will think that life as we know it will come to an end because our source of heat and energy is no longer in existence. Its true that life cannot survive without the Sun shining but let us ignore this aspect as well. Rather, let us see what will be the effect on the planet instead of the effect on living and non living things on the planet.

So reviewing what we have understood so far quickly, we note that the Sun has shrunk and become a black hole. This is a hypothetical case and we are ignoring the fact that the Sun does not have sufficient mass for this to happen. We are also ignoring the effect of the loss of sunlight on the lifeforms that exist on the Earth. Let us simply see what will happen to planet Earth. Will it get sucked into this black hole?

The first thought that may come to mind is that the Earth will spiral in and get destroyed. But what might be the cause of this? The Earth revolves around the Sun because of a balance between the gravitational force if feels from the Sun and its own angular momentum. For it to spiral into the black hole this balance has to be broken and gravity has to dominate. Since the angular momentum cannot change, gravity has to increase. Can this happen?

Long time ago, Newton told us that the gravity you feel is determined by two parameters. One is the mass of the object and the other the distance of that object from you. More the mass, more will be the gravity and more the distance less will be the gravity. Additionally Newton also showed that the mass of an object can be considered to be concentrated at a single strategically placed point. This point is called the center of mass. For spherical objects it is the center. So the gravity we feel on Earth would be the same gravity we would feel if the Earth shrunk to a point but we remained where we currently are – about 6400 km from the center (Refer to Fig 1). In much the same way, the Sun’s center is its center of mass. The gravity that the Earth feels due to the Sun can be thought of as arising from the Sun’s center of mass. This is very important point and will lead us to the answer we are searching for.

Figure 1

Even though the Sun has shrunk to a point, there has been no addition or reduction in its mass. Thus the gravity will not change because of this factor. What about the distance? That hasn’t changed either. The distance between the Earth and the Sun’s center of mass is still the same. Its just that instead of the mass being all around that point as in the case of the Sun, it is now concentrated only at the center of mass. So this wont change the gravity either.

If the gravitational force felt by the Earth does not change, there will be no change in its behavior. It will continue revolving as always around the newly formed black hole! None of the other planets would change the way they revolve (or rotate) either. The entire solar system will continue existing, with the sole difference that the Sun would no longer be shining.

There will be no change in the gravitational force till the region where the surface of the Sun once lay. Only beyond this point will the gravity be more than it originally was. (Refer to Fig 2) And here lies the notoriety of a black hole. Normally, an object would have hit the Sun’s surface and burnt away. Now, because there is no surface this object can get closer to the center without hindrances. And as it gets closer and closer, the gravitational force will start becoming greater and greater. Soon it will cross a limit where the gravity will become so strong that this object would now be unable to return. Even light faces this limiting boundary. It is called the event horizon. An asteroid, comet or spacecraft unfortunate enough to cross a certain limiting distance from the black hole will be lost forever. In any case, this limiting boundary would be fairly close to the center of our black hole, a long way inside from where the surface of the Sun had been. All objects far away can escape.

Figure 2

Thus only objects coming very close would be eaten up. Since the Earth is well away from the event horizon and its own limiting boundary, it will continue revolving around the black hole.

As the winter skies approach us and the clouds part after the rains it is time to head out for observations again. The winter skies are always special because of the abundance of bright constellations that include Orion – the hunter, Taurus – the bull, Gemini – the twins and Perseus – the warrior. One observation everyone will make is that all the stars do not have the same colour. While most appear white, some will have a reddish tinge to them while others may appear bluish. This can be easily seen with naked eyes and if you happen to have a small telescope, it will show you some stars that appear green while others that appear yellow. It is a colorful universe.

The colours of stars have a direct relation to their temperature. You can tell how hot a particular star is simply by studying its colour. But there lies one common source of confusion in this colour-temperature relation. Imagine you were looking at Betelgeuse, the bright red coloured star in the Orion constellation and Rigel, a blue coloured star also in the same constellation. Which would you classify as hotter?

Map of the Orion constellation. Betelguese is the star towards the top-left while Rigel is diagonally opposite, towards bottom right.

Over the years we have come to associate red colour as hot and blue colour as cold. This probably stems from our observation of burning objects that appear reddish-orange and water and ice that appear bluish-white. Perhaps there are some other cues that our mind has picked up. However if you compare the temperatures of objects burning with flames of different colours, you will almost shockingly notice that a blue flame is much hotter than a red flame. Of course there are certain conditions that dictate how these objects are burning but in general, emission of blue colour indicates a hotter temperature than the emission of red. Remember this applies only to objects generating their own light and not to most of our day to day objects that simply reflect light falling on them.

So coming back to the Betelgeuse and Rigel question, it is the calm and quiet looking Rigel that is hotter, shining brightly at 11,000 degrees Celsius. The red giant Betelgeuse at 3,500 degrees Celsius is much cooler. In fact as you start moving from blue to green, yellow, orange and red the temperature progressively decreases. This relation comes from the Planck Blackbody Curve which tells us how much light a star at a particular temperature emits at what colour. It is named after the German physicist Max Planck who first gave the relation.

The figure displays three "Planck Blackbody Radiation Curves" for three different temperatures. The peak of the curve representing the hottest temperature lies in blue colour while the peak of the lowest temperature curve lies in the red region. Objects that emit red colour are at a lower temperature than objects emitting blue colour

After the 22nd July 2009 eclipse, I was invited for an online chat on the Network 18 owned website, IBN Live. They invited the viewers  to submit questions which were put forward to me after a first level moderation. I was quite impressed by the quality of questions asked. The chat was supposed to go on for an hour but I was really enjoying myself so it went on for almost two hours. I have attached the transcript below. If you want to check the original transcript you can find it here. The questions are in reverse order, the first being right at the bottom.

Milinda:Just reading your experience of solar eclipse excites me here (reading this chat from office) in Pune & we are covered with think clouds and rains. The answer on – what was your immediate reaction – really gave me a experience of the occasion … that’s for writing back to us

Nikhil Pawar: Milinda, it was an experience of a lifetime. As I have written earlier the clouds did hamper us a bit but even then the experience was simply phenomenal. I realized that to see the entire sky go dark at 6:30 in the morning is something that you cannot prepare yourself for. As drenched as all of us were we were jumping and shouting with joy when the moon’s shadow fell on us. Just imagine standing under the shadow of the Moon. That alone is a incredible feeling. I am having withdrawal symptoms right now

Smiti:Sir,how long does the total phase of Solar eclipse last??? And what is Camera Obscura? Why is it harmful to see the eclipse with naked eye?

Nikhil Pawar: The total phase or totality may last anywhere between a few seconds to a few minutes. Depends of the position of The Earth and the Moon in their respective orbits. Camera Obscura is a pinhole projection technique that may be employed to view an eclipse safely. Simply take a sheet of paper, punch a small hole in it and let sunlight pass through it on to the ground. You will see an image of the Sun. You can check that it is actually the Sun’s image by cutting out triangular hole of square hole. You will always get a circular image on the ground. Thats because you are seeing an image of the Sun which appears circular. Make sure that the sheet is a little distance away from the ground. An eclipse is harmful to view directly because the Sun is emitting infra red rays and UV rays in addition to visible light. (at all times not just during an eclipse). These rays can harm the human eye. And you wont even know that your eye is getting hurt as it has no cells sensitive to pain!

anusha:to join in ur organization(SPACE), should we write any entrance xams?? can u tell us the various courses u offer n its duration??

Nikhil Pawar: SPACE is an organization dedicated to spread awareness about science. SPACE actually stands for (Science Popularisation Association of Communicators and Educators) We are a group of scientists and astronomers and educators who take astronomy and science to the masses. Check up more on one of our sister websites www.stepl.org

Ashwin Gangakhedkar:Hello Nikhil, I am reading your chat and it is indeed very informative and knowledge enriching. Being in Pune we missed out on the eclipse. But what effect does the eclipse have on earth’s gravitational force? Some predict abnormal behaviour of sea or even earthquakes. To what extent do these statements hold good?

Nikhil Pawar: Ashwin there are no known ill effects on the Earth during eclipses. remember it is just a normal New Moon day (amavasya). It just happens of occur right in front of the Sun. So gravitationally speaking it is not very different from any other new moon. Al these earthquake predictions are not credible. None of the recognized geologist groups have made such claims.

priyanka muralidharan:Is it true that lunar eclipses generally tend to last longer than solar eclipses….especially the moments of totality…any particular reason why that happens if it is true?

Nikhil Pawar: Yes. Lunar “totality” tends to last longer as the Earth is bigger than the moon and hence casts a bigger shadow. The Moon stays in this shadow for a longer time.

anoop kashyap:What does it mean by ‘the only Total Solar Eclipse of the century’? Does it mean there will be No Solar Eclipse for the whole world until 2132 or only for Asia ?? If so , Why ??

Nikhil Pawar: This is the longest eclipse of the century. Not the only eclipse. Total solar eclipses happen almost every year. This one is special because it is the longest eclipse of the century.

Milinda:We are enjoying the solar eclipse from earth ,is there someone (group) enjoying it from space / air?

Nikhil Pawar: Oh yes! For the first time in India the organization SPACE in association with Cox & Kings arranged an Eclipse Flight. We charterd a JetLite aircraft that took off from Delhi earlier today, intercepted the Moon’s shadow 41000 ft above Taregana near Patna. All the passengers got the best possible view of the eclipse. This concept of Astronomy Tourism has been brought to India by Mr Sachin Bahmba.

suni_D:is it safe to watch complete solar eclipse with naked eyes?

Nikhil Pawar: Only when the Moon completely covers the Sun, ie during totality, when not a single ray of sunlight is coming towards us is it safe to watch the eclipse with naked eyes. This happens only for a few minutes. Even if the eclipse is 99% partial one must view it with certifies solar goggles. So in a total eclipse like the one we got today, you must have solar goggles at all times (almost two hours) except for the 4 minutes of totality. The sunrays are very strong and can burn the retina if viewed directly.

Mrudula:why do eclipses last only for a few seconds or minutes normally?

Nikhil Pawar: The apparent (not actual) size of the Sun and Moon in the sky is roughly the same (half degree angular diameter). Due to this eclipses last only for a few minutes. If the moon would appear much bigger then the totality would be longer.

INDULEKHA PAWAR:THE SCIENTIFIC OFFICERS LIKE U AND YOUR COLLEAGUES MUST BE EXITED RIGHT NOW.WHAT IS YOUR EXPERIENCE

Nikhil Pawar: All the teams are excited. Though clouds blocked out some of the best features of an eclipse the experience was exhilarating. We experienced a day of to sunrises Students were screaming with excitement and jumping with joy just when we came under the shadow of the Moon. We were all drenched with rain but it just could not dampen our spirits.

Pankaj Giri:Is there any part time course available for amateur individuals to know more about Space.

Nikhil Pawar: There are amateur astronomy clubs in most cities of India. My organization SPACE is placed in Delhi, Hyderabad, Bangalore and Kolkata. You can join any of these clubs and learn more about astronomy and space sciences. Also check up our yahoo group called Astronomicans. Anyone interested can join it.

arun:Hi i have two questions for you. 1) will Solar eclipse cause any harm to planet earth in the from natural disaster and will it create negative energy in the psychological mind? 2) If not they why the astrologer and other people are spreading the wrong message and why scientist like you and ISRO not taking any action against this.

Nikhil Pawar: Arun there is absolutely nothing evil or negative about eclipses. astrologers earn a lot by scaring people. Time and time again scientists have battled against astrologers but it is up to people to adopt a scientific mind set and get rid of this superstitions. Till the people listen, the astrologers will spread misinformation.

Smiti:What is the effect of solar eclipse on Animals ???

Nikhil Pawar: Bird and animal behavior has been tracked for quite a while now. Birds especially tend to get confused when totality hits. Animals also sense something off and get restless and anxious. As more and more data comes in we will learn more about how they react.

anusha:since satellites have to work on batteries during solar ecclipse, how is this longest solar eclipse going to effect the satellites?

Nikhil Pawar: satellites are used to stay for long hours in the absence of sunlight. Remember that satellites survive through the night as well. So a few minutes of Moon shadow does not affect them at all.

Preeti Pardeshi:Since you were in Patna I’m hoping you saw the eclipse in totality! Please fill us in on how it felt to watch this awesome phenomenon!

Nikhil Pawar: There were clouds from about 4:30 am in Patna. so the view of the Sun was blocked. In fact it even started raining and all of us got drenched while trying to protect our equipment. The Sun was supposed to be covered completely by the Moon at 6:24 am. That was the start of totality as it is called. The rain stopped about 4 minutes before this time. We started a ten second countdown in anticipation of totality not knowing what to expect. The second we hit 3…2…1…0… the sky suddenly turned dark as night. we were surprised by the level of light intensity drop. It stayed as dark as night for about 3.5 minutes and exactly at the predicted moment, totality ended and the light returned just as suddenly as it had disappeared. We couldn’t see the Sun but this entire darkening was simply phenomenal. Ironically the sky cleared a bit after totality giving us a few glimpses at the partially eclipsed crescent Sun.

Milind Pawar:Hi Nikhil, keeping in mind that sun goes out for few minutes, however – does the moon gravity creates any prism kind of effect on the sun rays – @ which we are yet to be fully aware – which can cause changes in atmosphere –

Nikhil Pawar: Einstein’s General theory of relativity does predict bending of light by massive objects but more than the Moon it is the Sun that exhibits this. Very precise observations show that the Sun creates a gravitational lens and bends light coming from background star by a very small amount. The Moon is too small to create this gravitational lens that can be observed.

priyanka muralidharan:You did say that you’ll had quite a few experiments planned during the eclipse, but the rain played spoil sport.Can you tell us which experiments can be conducted during an eclipse and especially small experiments which can probably be performed at home by school children?

Nikhil Pawar: We planned to track changes in air temperature, soil temperature, wind speed, humidity and light intensity. All these are quite simple to perform. The equipment needed is readily available and the data that you collect is very significant to understand how the atmosphere reacts to the umbral shadow (shadow of the Moon. we had planned these experiments at Patna and china (the two places where we sponsored students to go on a scientific expedition)

Joyeeta:As this solar eclipse is the longest one, can you explain its importance? Astrology prediction shows many advantages and disadvantages. Do you believe in astrology predictions?

Nikhil Pawar: All astrologers do is spread panic and misinformation. They have no proof for any of their claims and no scientific basis. I do not believe in astrology and anyone who holds reason and rationality as their highest virtues will see the hoax of astrologers. Please do not believe a single word they say. there is nothing evil about eclipses.

ashokpawar:How to educate masses on superstitions about eclipse?

Nikhil Pawar: The best way is to educate students. And education does not just mean “telling” them to view an eclipse. They must be given reasons and they must be made to understand the phenomenon of eclipses. Once they understand the science behind it, they will throw away the superstitions themselves. Women must also take the initiative to learn more about this phenomenon. They hold a lot of power to educate their families. Public and pvt organisations must organize mass events. It will create publicity for them as well as spread awareness in society.

Preeti Pardeshi:Hi Nikhil, Im guessing this is what you’ve wanted to do ever since you were a child! What advice to you have for budding astronomers?

Nikhil Pawar: Even a clouded out eclipse was worth all the effort the entire team of astronomers from SPACE took for the past few months. It was an exhilarating feeling. All young students should concentrate on pure sciences, not get distracted by all the baseless rumors spread out by some sections of society and look forward to experiencing all aspects of astronomy. Go out for night observations, pick up a telescope and satisfy your curiosity. You will be amazed at how much there is to discover and enjoy in astronomy. There is a lot more to astronomy than just eclipses and starry nights. If not professionally, at least every student should pick astronomy as a hobby.

anusha:good moning Mr.nikhil pawar! during night times we see moon. when moon covered the sun during solar eclipse, why cant we see moon?

Nikhil Pawar: The Moon does not have light of its own. It reflects the the light of the Sun. This is why we see different phases of the Moon. During an eclipse, the side facing away from the Earth gets sunlight as the Sun is behind the Moon. The side facing us has no sunlight falling on it. Hence we cannot see the Moon. Incidentally all solar eclipses happen on a New Moon day and all lunar eclipses occur on a Full Moon day.

Divyesh:What is your first expression after this eclipse?

Nikhil Pawar: This was my first total solar eclipse. I had already seen an Annular Eclipse, a partial solar eclipse and lunar eclipses. So needless to say I was looking forward to it. Everyone in our organisation was preparing for it for the past few months. Unfortunately at Patna, clouds blocked the views of the diamond ring and corona of the Sun. But even then the dramatic sudden drop in light intensity amazed me. All of us just gave a collective expression of “Whoa!!” at the light intensity change. It was much more than what we had expected and very sudden.

Gopal Das:What is the average duration for a lunar and solar eclipse?

Nikhil Pawar: A total solar eclipse will typically last for 2 hours (5:30 IST to 7:30 IST for the 22nd July eclipse in India). This is from a point the Moon just touches one edge of the Sun till it crosses over and leaves the other edge. The period for which the entire Sun is covered by the Moon will tend to vary from as little as a few seconds to a maximum of 7 min and 29 sec

satanmig:It is said that a Solar eclipse occurs every 18 months on an average. Is this figure correct and if so then can a periodic calendar be drawn up to see more eclipses?

Nikhil Pawar: A solar eclipse in fact happens approximately once every 6 months. We had one in Jan, today’s was six months later. Again we have an annular solar eclipse in Jan 2010. So yes a periodic timescale exists. It helps us predict eclipses. There is another periodic cycle called the Saros Cycle. According to this cycle, the same eclipse will repeat itself in about 18 years and a few days but over some other location of the Earth. thus all eclipses have a saros number.

Gopal Das:What is the longest a total solar eclipse can last?

Nikhil Pawar: Remember the orbit of the Earth and the Moon is elliptical. If the Moon is closest in its orbit around the Earth and the Earth is farthest in its orbit around the Sun, we will get the longest eclipse. The maximum duration can be 7 min and 29 sec. An eclipse of this duration is predicted on July 16, 2186.

Kuntal:Where will the next total solar eclipse occur?

Nikhil Pawar: The next total solar eclipse will be on Sunday, 2010 July 11. It will be visible from within a narrow corridor that traverses Earth’s southern Hemisphere. The path of the Moon’s umbral shadow crosses the South Pacific Ocean. It does not hit any landmass except for Mangaia (Cook Islands) and Easter Island (Isla de Pascua). The path of totality ends just after reaching southern Chile and Argentina.

kamini:Is this event more exciting for astronomers or astrologers?

Nikhil Pawar: Interesting question. While astronomers across the world prepare for months together in anticipation of an eclipse such as this, astrologers tend to just spread fear by announcing all the evils that an eclipse will cause. There is no scientific basis to their claims and they have no proof either. So they probably just try to cash in on some publicity. They have little to do with the actual event. The event itself is a big moment for astronomers. I spent a sleepless night last night in anticipation of this eclipse. My entire team was as excited as I was. The solar corona, diamond’s ring and all the other phenomena are just too tempting

Preetam:What scientific discoveries are expected from the eclipse?

Nikhil Pawar: Long time ago Einstein’s General Theory of relativity was proved during a solar eclipse by looking at the slight change in the position of stars near the Sun due to light bending. This is a phenomenon that Einstein’s theory predicted. Helium was also discovered during a solar eclipse. These days the solar corona is studied extensively during eclipses. The Moon’s limb can also be studied in detail during an eclipse. weather changes are also studied and tracked during eclipses

suni_D:Do you think that this solar eclipse will have severe effect on whether for few days?

Nikhil Pawar: Hi Suni. Solar Eclipses do not have any known long term effect on the weather as the sun only goes out for few minutes, while during the night it remains missing for a few hours. Earths atmosphere however does go into a kind of a shock because of cutting of the sun light quite quickly. For example, in our eclipse journeys we have measured temperature drops of about 7 degrees, change in wind speeds etc.

Its the eclipse season again. The longest total solar eclipse of the century is on 22^nd of July. Citizens of India will get a first hand view of this spectacular phenomenon as the path of total solar eclipse (or totality as it is called) passes right through the breadth of India. Starting from the western tip of Gujrat the eclipse will pass right across the country before moving off to China. Most parts of India will see either a total or partial solar eclipse.

Like always, this eclipse will also bring a lot of superstitions and myths with it. While some television channels will portray the evil nature of eclipses, others will have alleged experts telling you which chant to recite and what rituals to follow to stop this evil from harming you. Those who are ignorant of the true nature of eclipses will issue warnings asking you not to eat food, not to hold a knife in your hand, to take a bath in holy waters and ask pregnant women to stay indoors. Even a school student with some basic knowledge of science can tell you that these are all superstitions and myths. None of this is true.

Eclipses are spectacular events and must be enjoyed by all. You must make a journey to a place where a total solar eclipse is visible and gain an experience of a lifetime. There is hardly a sight better than a total solar eclipse. But there are certain precautions that need to be taken during a solar eclipse. Observing the Sun can be dangerous if you do not take proper care.

Reaching the surface of the Earth from the Sun, in addition to the visible light, are some ultra violet (UV) rays and a bit of infra red (IR) rays. It is UV rays that cause your skin to tan while the heat that we feel when we are out in the Sun is due to IR rays. So these come to us all the time. During an eclipse, if you stare at the Sun without protection, the retina of the eye can get damaged. The tissue of the eye transmits all the light falling on it. Excessive light may trigger a complex chemical reaction in the light sensitive cone and rod cells of the retina which may damage them. This will result in temporary or sometimes even permanent loss of vision.

If you stare at the Sun for a long duration, the IR rays will end up cooking the eye tissue and the retina. IR carries so much heat that it can cause permanent burn injuries to the retina creating a blind spot in the eye or even complete loss of vision in some cases. Incidentally the human eye does not have pain receptors. This means that while the eye is being cooked, you will not feel any pain and the effects of the injury might show up several hours after the actual damage.

The best way to observe the Sun is by using certified solar filters. These filters will clearly mention that they are designed for safe solar viewing. There are many unsafe filters that are sometimes suggested like photographic films, X ray films, smoked glass and sunglasses. All these are ineffective and using these or a combination of these as solar filters is extremely risky.

You must wear certified solar filters at all times during an eclipse. The only time it is safe to remove the filters is when the Moon has completely covered the Sun. This happens for a few seconds to a few minutes at mid eclipse if you are in the path of totality. But keep a track of how long the totality will last and put your filters back on a few seconds before the end of totality.

A solar eclipse is like the festival of Diwali. While there are certain risks involved, if the necessary precautions are taken they tend to the most memorable experience of your life. Make sure you are in the path of totality this 22^nd July and use proper solar filters to observe the eclipse.

“What is the magnification of this telescope?”

Now the question is not an incorrect one to ask, but I have realized that most of the times the thought behind the question is wrong. Many of us associate a telescope with the word magnification. Many think that a good telescope is one which provides very good magnification. This is a misconception.

The most important function of a telescope is not magnification. It is an important aspect, but not one which determines the quality of a telescope. The highest priority is given to the aperture of a telescope. Aperture is the size of the primary lens or mirror. In general, bigger the aperture better the telescope.

Celestial objects are very far away from us. Very little light reaches us from these celestial objects at night. So our aim in building a telescope is to collect as much light as possible from these faint objects, hence the importance of aperture or the size of the mirror or lens that collects light.

Our eyes have a small pupil which lets light go through. Our eyes have evolved to see in normal daylight conditions. But when we go out under the night sky, our eyes are just too small. We need to collect a lot of light and since we cannot increase the size of our eye, we funnel the light using a telescope.

Once our telescope has collected enough light, we see it through an eyepiece. This is where magnification comes in. By changing the power of the eyepiece, various magnifications can be achieved for the same telescope. Even a small telescope can give high magnification if you put a powerful eyepiece on it, though this is of no use to us because it would have collected very little light and hence the image quality would not be good. Magnification is helpful only after the telescope has collected sufficient light, which is controlled by the aperture. Typically an aperture of 8-inch is considered good for amateur astronomy. So the next time you see a telescope, ask what is its aperture.

(Cartoon by Tyler Nordgren. Source: NOFS/NPOI)

Shooting stars or meteors as they are scientifically referred to, are tiny bits and pieces of debris that have been floating around since the formation of the solar system. These happen to be on a path that intersects with the Earth and when that happens they enter the Earth’s atmosphere and burn brilliantly. When floating in space they are referred to as meteoroids, when they enter the Earth’s atmosphere they are called meteors and if they impact the ground then they are called meteorites. Their origin can sometimes be traced to a comet leaving a trail of dust along the path it has taken around the Sun or to an asteroid. Both these objects formed early in the solar system and hence meteorites are studied to find more answers about the early conditions of our solar system.

Millions of meteors enter the Earth’s atmosphere every day. Most of the meteors are the size of a tiny pebble. Some of the larger ones reach the Earth’s surface – the meteorites. These meteorites are classified in three categories depending on their composition. These categories are stony, iron and iron-stony. Stony meteorites are silicon dominated with little or no iron. The iron meteorites mostly contain iron and nickel while the iron-stony have an equal composition of silicon and iron. The difference arises from the different origins of these meteorites.

On any clear dark night you should be able to see about 5-10 meteors every hour. They look like stars falling from the sky and hence the common name. They leave a trail behind as the burn in the Earth’s atmosphere. They are a beautiful site for everyone and I would highly recommend that you try and spot a few on your next overnight outing. Needless to say they do not have the power or the luxury to grant you your wish, should you make one on seeing them.

Moon, Venus, Jupiter Conjunction on 1st Dec 2008

The conjunction image after basic image processing

A picture I took from Hyderabad on 1st Dec 2008. It was quite late when I managed to get my hands on one of my colleague’s regular hand held Fujifilm Finepix camera which is a 6.3 Megapixel camera.  Unfortunately I got the right settings for a picture like this very late and by that time the three objects had reached very close to the horizon.

Moon of course can be easily identified and of the two objects above the Moon, the brighter one on the left is Venus and the fainter one to the right is Jupiter.

For long scientist have struggled to answer the question about the origins of the universe. The most popular theory till date – the Big Bang theory states that everything and that means everything including matter, energy and the vast empty space originated at the time of big bang. It is a difficult concept to imagine that this vast space itself did not exist before the big bang, but that is what the theory states. It is often said that life is stranger than fiction and this would be a very good example.

We do not know what triggered the big bang but we have a fair estimate of what happened after a few minutes from the big bang. Space started expanding rapidly. The temperature was really high. First there was a thick soup of matter and energy all mixed and together. Matter is nothing but all the atoms and electrons, that is all the “stuff” that we see around us. While energy is something we experience in the form of electricity or heat. Today these two do not mix and interchange all by themselves. But after a few minutes from the Big Bang these two were together and all mixed up in a thick hot primordial soup. Matter was not structured as we see today but in tiny little pieces. Smaller than atoms, smaller that the atomic nucleus!

As the universe expanded, it cooled. At that time, matter which was in the form of a raw material started building the first nuclei. As the universe cooled further the nuclei started forming bigger and bigger blocks and after about 13.5 billion years we reached where we are today.

The mystery ingredient

It seems that this is a nice way to cook up all that there is around us. But our observations have shown that the above process forms only 4% of the ingredients of our universe. The remaining 96% is missing!

This missing quantity is in the form of Dark Matter (26%) and Dark Energy (70%). These, we cannot see but only detect using indirect techniques. If only we could go back to the Big Bang and see what happened.

CERN and their flamboyant plan

CERN which stands for Conseil Europeen pour la Recherche Nucleaire (in French) or European Organization for Nuclear Research (in English) is one of the world’s best particle physics research center. The CERN Laboratory is located at the France-Switzerland border near Geneva.

Scientists at CERN have planned an experiment to recreate the conditions just after the Big Bang. With their experiment they will recreate the primordial soup and watch the formation of the first nuclei. With this they will have answers to how atoms and other building blocks first formed. This will also allow them to see how this raw material resulted in the formation of the mysterious dark matter and dark energy. The experiment will use the Large Hadron Collider (LHC).

The Large Hadron Collider(LHC)

This is a huge underground instrument which is in the shape of a ring and has a circumference of over 26 kilometers. The temperature of the LHC is as low as 271 degree Celsius below zero (-271 degree Celsius). This giant instrument is as empty as interplanetary space. This is done to avoid gas molecules and other particles interfering with the experiment.

The awesome experiment

The LHC will start accelerating protons inside it using huge superconducting magnets. These protons will travel at 99.99% the speed of light and will go around the 26 kilometer accelerator 11,245 times every second making the LHC the fastest racetrack in the world.

At its fastest, protons will start colliding with one another and will create temperatures over 100 000 times hotter than the heart of the Sun, right inside the accelerator. Thats around 2000 billion degrees (2000 with 9 zeros after that!) This will mimic the early universe. The way it was just after the big bang.

Black holes and the end of the world

A lot of hype has been created by this experiment and many claim that on 10^th September 2008 when the accelerator is turned on one or many black holes will be created eating the entire Earth. Scientist at CERN have dismissed these claims saying that the experiment will pose no risk to the Earth. Cosmic ray collision happen frequently in the Earth’s atmosphere. These collisions produce energies in excess of what the LHC will produce. Thus if these collisions were to have destructive effects, the Earth would have ceased to exist long time ago.

Some speculative theories suggest that microscopic black holes may be created due to this experiment but it is the same theories that suggest these black holes would disintegrate immediately. The LHC would not be able to create anything that hasn’t already happened in nature. It will just be in a laboratory for the first time. The continued existence of other stars and the Earth itself rules out the possibility of the LHC creating destructive black holes.

So what to expect

Many people are eying 10^th September as the day when a groundbreaking discovery will be made. However on this date the LHC will simply be tested. A stream of particles will be accelerated clockwise. After this round of testing a beam will be sent accelerating anticlockwise around the accelerator. Incidentally the collider has been cooling itself for the past 6 weeks to reach the desired temperature. As per the current schedule it will be on 21^st October 2008 that the beams will be fired simultaneously to start the collisions.

It is on this day that nestled deep underground, in the Alps near the lovely Geneva, the world’s most powerful atom-smasher will get down to its main purpose. Of defying nature and re-enacting the Big Bang – the theory that a colossal explosion created our universe.

The circumference of the LHC sketched over an ariel view of French-Swiss countryside. LHC itself is buried deep underground.

Author’s Note:

Due to a technical glich with thier system, the testing has stopped since about mid september. To get the LHC to working temerature will take a long time again and with winter approaching, energy needs to be saved. So the experiment has been put on hold till spring/summer 2009.

But as you move into the realm of serious amateur astronomy, it is not just the view that you are interested in. You want to understand, comprehend and study what you see. You want to explain the phenomenon that you see. You want to know everything that there is to know about the objects you see.  It is this curiosity of the human mind that has helped us survive in this world. It is this curiosity that helps us make breakthroughs in science and technology. And through such breakthroughs we learn more and more.

One such breakthrough gave us the world of radio astronomy. It gave us a look at the universe using a new eye; a radio eye. The human eye and most of the aids we use to observe operate in what is known as the ‘visible’ or ‘optical’ part of a wide spectrum. It was known for quite some time that there are other sections of this spectrum that exist but nobody had ever tried using these to observe the sky. In fact it was believed that there wouldn’t be any significant signal that one would receive if tried to observe in non optical regions. This combined with the absence of developed technology resulted in astronomy being carried out only in the optical region. But post World War with the development of the radar, radio astronomy shot to fame.

A radio astronomer doesn’t use telescope with a mirror and stare out at the sky just at night. He uses huge dish antennas with large receivers that stream radio signals that they catch from the sky onto computers and give him a radio signal. This radio signal is mostly in the form of a graph showing the amount of signal coming from the sky at any given time. Though the name radio astronomy might bring to mind a radio astronomer sitting under a radio telescope with headphones, listening to radio waves, this is not at all true. Radio astronomers rarely ‘listen’ to a radio signal. Radio waves are information carriers and they can carry sound as in the case of commercial FM radio channels or can carry visual signals as in the case of direct-to-home (DTH) satellite televisions. But the radio signals that come to a radio telescope from the universe mostly carry information about the conditions that prevail in that part of the universe.

So what does a radio astronomer look at, that an optical astronomer might miss?

Imagine a radio astronomer is scanning the sky for radio signals. He is moving his antenna from the direction of Orion constellation towards Auriga. Suddenly, as the telescope is passing the Taurus constellation, there is huge spike on his computer screen. The radio telescope found something! Wide eyed, he tries to figure out where the telescope was exactly. He stops it from moving and takes it back to that position in constellation Taurus. As the telescope slowly moves into position, there is a spike again. And again, and again! Like a heart beat. There are spikes on the screen at regular intervals. The spikes are actually coming really fast, but the computer is slowing it down for him. He checks the actual speed at which the spikes are coming. There are 30 spikes every second. “Wow! That is fast” he thinks. Like a heart that is beating really fast. Our astronomer has found the Crab Pulsar.

It is an extremely fast rotating object, also called as a neutron star because its made up of neutrons. It is one of the possible end stages of big stars. Stars much bigger than our Sun. When they finish their fuel, they tend to explode and shed their outer layers while a super dense core remains. This super dense core is about the mass of our Sun but only about 10 km in diameter. So pulsars are very small objects. They are rotating rapidly, have very strong magnetic fields and give out radio waves from their magnetic poles. The magnetic axis is most often not the same as the rotating axis and hence these radio waves reach us once or twice every rotation cycle. Like a lighthouse sweeping its light beam at us once every rotation. Pulsars are difficult to spot using optical telescopes but are fairly easily seen by radio astronomers.

Now our astronomer keeps observing the Crab Pulsar till it sets and starts searching the sky for more objects. As he goes east, the constellation Cygnus has risen. “Maybe there is something interesting here”, he thinks. And sure enough, his telescope spots something. It is not a simple signal. His computer analyzes the signal and gives him an image, a picture, of a small part of the sky in Cygnus. What he sees is an incredible view. Two large clouds of that seem connected to one another through a thin strand with a bright spot at the center. Is that a nebula? He checks the distance. It is outside our galaxy! It can’t be a nebula. It has to be another galaxy. It is a radio galaxy, with huge lobes on either sides of it. The bright spot in the middle is the galaxy, and from this galaxy large jets are streaming out on either side. These jets terminate and form the large lobes that are much bigger than the parent galaxy! “How does this happen?” he wonders. There is a super massive black hole at the center of this galaxy. And as this black hole eats matter from the galaxy, two large jets are created due to matter spiraling in so quickly and shoot out of the galaxy emitting strong radio waves. The name of this galaxy is Cygnus A.

Apart from pulsars and radio galaxies, the radio astronomers can also observe many different objects. Hydrogen gas clouds become visible in the radio region. Black holes can be inferred, planets studied and even the Sun can be an interesting radio source to observe. That is how a radio astronomer spends his day. Observing through a telescope and analyzing the data he collects for weeks till some new information is discovered.

Cygnus A - A lovely radio galaxy showing two massive lobes at the ends of two jets arising from the tiny looking galaxy in the center