Monthly Archives: May 2010

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Astronomy Events for June 2010

May 31, 2010 12:41 PM ⋅ Leave a Comment ⋅
June 3 : Moon at apogee (farthest from Earth) at 17h UT (distance 404,266 km; angular size 29.4').
June 4: Last Quarter Moon at 22:13 UT.
June 6: Moon near Jupiter (morning sky) at 4h UT. Mag. -2.3.
June 7: Mars 0.8° NNE from Regulus (74° from Sun, evening sky) at 6h UT. Mags. +1.2 and +1.3.
June 8: Jupiter 0.44° SSE from Uranus (77° from Sun, morning sky) at 8h UT. Mags. -2.3 and +5.9.
June 10: Mercury 5.9° SSE of the Pleiades (19° from Sun, morning sky) at 16h UT. Mag. -0.4.
June 10: Moon near Pleiades (morning sky) at 23h UT.
June 11: Moon near Mercury (morning sky) at 1h UT.
June 12: New Moon at 11:15 UT. Start of lunation 1082.
June 15: Moon near Venus (evening sky) at 4h UT. Mag. -4.0.
June 15: Moon at perigee (closest to Earth) at 15h UT (365,931 km; 32.7').
June 15: Moon near Beehive cluster (M44) (evening sky) at 17h UT.
June 17: Moon near Regulus (evening sky) at 4h UT.
June 17: Moon near Mars (evening sky) at 15h UT. Mag. +1.3.
June 19: First Quarter Moon at 4:29 UT.
June 20: Venus 0.7° from Beehive cluster (M44) (evening sky) at 20h UT. Mag. -4.0.
June 21: Moon near Spica (evening sky) at 1h UT.
June 21: June solstice at 11:29 UT
ie.The time when the Sun reaches the point farthest north of the celestial equator marking the start of summer in the Northern Hemisphere and winter in the Southern Hemisphere.
June 24: Moon near Antares (evening sky) at 12h UT.
June 26: Full Moon at 11:30 UT.
June 26: Partial Eclipse of the Moon from 10:17 to 13:00 UT, mid-eclipse at 11:38 UT. Visible from the Americas, the Pacific and eastern Asia.
June 28: Mercury at superior conjunction with the Sun at 12h UT. The planet passes into the evening sky.
All times are in terms of Universal Time (UT).
V S/AASTRO
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25 Random Things About…… The Milky Way

May 18, 2010 9:13 AM ⋅ Leave a Comment ⋅

1. In Greek Mythology, the Milky Way was created by milk spilled when Hera, the wife (and sister!) of Zeus, was nursing Hercules.

2. Wherever you live in the world, and whatever the season, if you have dark sky you can step outside on a clear night and see the nearby spiral arms of the Milky Way.

3. The center of the Milky Way is in the direction of Sagittarius, which is low on the horizon for observers in the Northern Hemisphere. But near the equator, or in the Southern Hemisphere, the center of the Milky Way is almost directly overhead… a spectacular sight!

4. Most of us learned the Milky Way is a type of spiral galaxy.  But in the past few years, astronomers discovered our galaxy is not just a spiral, but a barred spiral galaxy of type SBbc.

5. The Milky Way has a diameter of 100,000 ly.

6. And it’s about 1000 ly thick.

7. Our solar system lies close to the plane of the Milky Way, which means the Milky Way seems to split the night sky into two equal halves.

8. Aristotle believed the Milky Way was caused by burning stars in the upper atmosphere.  While he was a fine philosopher, many of Aristotle’s scientific conjectures were way off.

9. There are about 300 billion stars in our galaxy.

10. The Sun lies about 26,000 ly from the center of the Milky Way.

11. The Sun rotates once around the Milky Way every 220 million years.  Our solar system (and therefore the Earth) revolves about the galactic center at 220 km/s.  At this speed, our solar system travels in the direction of the star Vega at a rate of one light-year every 1400 years.

12. The oldest stars in the Milky Way lie near the centre of the galaxy and in a halo about the centre, which consists of globular clusters and lone ancient stars.

13. Along the spiral arms, away from the galactic center, interstellar clouds collapse under the force of gravity into tight fists of gas and dust that ignite into fresh new clusters of stars.

14. As you read this, the Milky Way is colliding with an obscure dwarf galaxy named the Virgo stellar stream.

15. At the center of the Milky Way lies a gigantic black hole with a mass of 4 million suns that is violently gobbling stars and matter and sending out highly energetic  X-rays.  But the Earth is in no danger of colliding with this black hole… so don’t worry.

16. Our solar system lies along the inner rim of the Orion Arm of our galaxy.  The next arm closer to the center is the Carina-Sagittarius arm, and the next arm farther away from the solar system is the Perseus arm.

17. The name for the Milky Way in China, Japan, and other East Asian cultures, is “Silver River” (a much more accurate name, don’t you think?).

18. The north and south Galactic poles, which point 90 degrees away from the dusty galactic plane, lie in the constellations Coma Berenices and Sculptor, respectively.  When you look in the sky towards the poles and away from the galactic plane, you can see into deep intergalactic space where lies millions more galaxies of all shapes and sizes.

19. Galileo was the first to discover the Milky Way is made of stars.

20. The Milky Way and Andromeda galaxy are the largest  in what’s known as the Local Group of galaxies.  In the Local Group, there are many tiny dwarf galaxies, the largest of which are the Large and Small Magellanic Clouds.  The Local Group of galaxies is itself part of a much larger cluster of galaxies called the Virgo Supercluster.

21. The Andromeda Galaxy approaches our Milky Way at 100 km/s, and the two giant galaxies will collide in roughly 2 billion years.  The stars in each galaxy won’t collide, but the two galaxies will merge into a featureless elliptical galaxy and lose their beautiful spiral shape and the dust and gas that form new stars.

22. From Thoreau, a beautiful quote to console you when you’re alone with your telescope, wondering if anyone will ever understand why you love the stars so much: “Why should I feel lonely: Is not our planet in the Milky Way?”

23. Most of the mass of the Milky Way is believed to consist of mysterious “dark matter”, the nature of which is still unknown.

24. The oldest star in the Milky Way, called HE 1523-0901 in Libra, is some 13.2 billion years old, almost as old as the universe itself.

25. Because of the effects of light pollution, most children in the world will never see the Milky Way.

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The Mule Driver Who Measured the Universe

May 18, 2010 8:50 AM ⋅ Leave a Comment ⋅

Milton Humason

Milton Humason was born in Dodge Center, Minnesota in 1891.  When he was 14 years old, his parents sent him to a summer camp on Mount Wilson, near Los Angeles.  The mountain’s forests and soaring views of southern California stole the heart of the prairie boy.  He convinced his parents to let him take a year off school to stay on the mountain and find work.

He never returned to school.Instead, Humason took up work as a mule driver, hauling lumber up a trail from the Sierra Madre to Mount Wilson to build the new astronomical observatory… an enormous project organized by the astronomy pioneer George Ellery Hale.In 1911, Humason’s heart was stolen once more: he became engaged to Helen Dowd, the daughter of the chief engineer of the observatory on Mount Wilson.  They married shortly after.  He left to work as a foreman on a ranch in nearby LaVerne.  But he missed the mountain.  In 1917, Humason saw his chance to return and to impress his father-in-law:  he took a position as observatory janitor.  This was a big step up from mule driver and ranch hand.Soon after, the new observatory posted a position for “night assistant”, which is essentially a helper for astronomers who need to operate the telescope and observatory dome. Humason took up the role.  His patience and skill and diligence brought him to the attention of Hale himself.  In 1919, in the face of stern protests, Hale appointed Humason… a high-school dropout… to the scientific staff of the observatory.  Humason remained in the role until 1954.

Humason worked with Hubble, and later Hubble’s protege, Allan Sandage, to study the spectral redshift of hundreds of galaxies to determine how fast they were receding… their so-called “radial velocity”.   Hubble (correctly) believed the radial velocity of a galaxy was related to its distance, a relationship now known as “Hubble’s Law”.But these far-away galaxies had low surface brightness, and were notoriously hard to measure.  So Humason developed techniques to optimize the photographic exposures and plate measurements. He determined the radial velocities of 620 galaxies, and helped set the distance scale and age of the universe.   Much of Hubble’s success was attributed to Humason’s painstaking measurements.

For his achievements, Humason was awarded an honorary doctorate from the University of Lund in Sweden.  He retired in 1957, and died in Mendocino, California, in 1972 at the age of 80.

featured in  ONE MINUTE ASTRONOMER

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Is Time Travel Possible?

May 17, 2010 9:17 PM ⋅ Leave a Comment ⋅

Time travel is the concept of moving between different points in time  in a manner analogous to moving between different points in space, either sending objects backwards in time to some moment before the present, or sending objects forward from the present to the future without the need to experience the intervening period.This is a common theme in science fiction, of course, but the real science is actually quite complex and intriguing.The question here is : Is Time Travel Possible?  The short answer is "Yes," but it's a heavily qualified "Yes."

Though referenced in H.G. Wells' The Time Machine (1895), the actual science of time travel didn't come into being until well into the twentieth century, as a side-effect of Einstein's theory of General relativity (1915). Relativity describes the physical fabric of the universe in terms of a 4-dimensional space-time, which includes three spatial dimensions (up/down, left/right, and front/back) along with one time dimension. Under this theory, which has been proven by numerous experiments over the last century, gravity is a result of the bending of this spacetime in response to the presence of matter. In other words, given a certain configuration of matter, the actual spacetime fabric of the universe can be altered in significant ways.

One of the amazing consequences of relativity is that movement can result in a difference in the way time passes, a process known as time dilation. This is most dramatically manifested in the classic Twin paradox. In this method of "time travel" you can move into the future faster than normal, but there's not really any way back.

Early Time Travel

In 1937, Scottish physicist W. J. van Stockum first applied general relativity in a way that opened the door for time travel. By applying the equation of general relativity to a situation with an infinitely long, extreme dense rotating cylinder (kind of like an endless barbershop pole). The rotation of such a massive object actually creates a phenomena known as "frame dragging," which is that it actually drags spacetime along with it. Van Stockum found that in this situation, you could create a path in 4-dimensional spacetime which began and ended at the same point - something called a closed time like curve - which is the physical result that allows time travel. You can set off in a space ship and travel a path which brings you back to the exact same moment you started out at.

Though an intriguing result, this was a fairly contrived situation, so there wasn't really much concern about it taking place. A new interpretation was about to come along, however, which was much more controversial.

In 1949, the mathematician Kurt Godel - a friend of Einstein's and a colleague at Princeton University's Institute for Advanced Study - decided to tackle a situation where the whole universe is rotating. In Godel's solutions, time travel was actually allowed by the equations ... if the universe were rotating. A rotating universe could itself function as a time machine.

Now, if the universe were rotating, there would be ways to detect it (light beams would bend, for example, if the whole universe were rotating), and so far the evidence is overwhelmingly strong that there is no sort of universal rotation. So again, time travel is ruled out by this particular set of results. But the fact is that things in the universe do rotate, and that again opens up the possibility.

Time Travel and Black Holes

In 1963, New Zealand mathematician Roy Kerr used the field equations to analyze a rotating black hole, called a Kerr black hole, and found that the results allowed a path through a wormhole in the black hole, missing the singularity at the center, and make it out the other end. This scenario also allows for closed timelike curves, as theoretical physicist Kip Thorne realized years later.

In the early 1980s, while Carl Sagan worked on his 1985 novel Contact, he approached Kip Thorne with a question about the physics of time travel, which inspired Thorne to examine the concept of using a black hole as a means of time travel. Together with the physicist Sung-Won Kim, Thorne realized that you could (in theory) have a black hole with a wormhole connecting it to another point in space could be held open by some from of negative energy.

But just because you have a wormhole doesn't mean that you have a time machine. Now, let's assume that you could move one end of the wormhole (the "movable end). You place the movable end on a spaceship, shooting it off into space at nearly the speed of light. Time dilation (see, I promised it would come back) kicks in, and the time experienced by the movable end is much less than the time experienced by the fixed end. Let's assume that you move the movable end 5,000 years into the future of the Earth, but the movable end only "ages" 5 years. So you leave in 2010 AD, say, and arrive in 7010 AD.

However, if you travel through the movable end, you will actually pop out of the fixed end in 2015 AD. What? How does this work?

Well, the fact is that the two ends of the wormhole are connected. No matter how far apart they are, in spacetime, they're still basically "near" each other. Since the movable end is only five years older than when it left, going through it will send you back to the related point on the fixed wormhole. And if someone from 2015 AD Earth steps through the fixed wormhole, they'd come out in 7010 AD from the movable wormhole. (If someone stepped through the wormhole in 2012 AD, they'd end up on the spaceship somewhere in the middle of the trip ... and so on.)

Though the most physically reasonable description of a time machine, there are still problems. No one knows if wormholes or negative energy exist, nor how to put them together in this way if they do exist. But it is (in theory) possible.

Ref : Andrew Zimmerman Jones' article on time travel

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AASTRO Wayanad will have a study session on “The Sun”

May 15, 2010 12:46 AM ⋅ Leave a Comment ⋅
 

The sun is one of over 100 billion stars in the Milky Way Galaxy. It is about 25,000 light-years from the center of the galaxy, and it revolves around the galactic center once about every 250 million years.

As a part of their Monthly study sessions,AASTRO Wayanad will take up the topic "The sun" on a get together at Kolagappara on May 16th.The discussion will be headed by experts and academicians and AASTRO members,students,astronomy enthusiasts and amateur astronomers from all over the district will take part.The meet will commence by 3 o' clock in the evening.AASTRO Wayanad chapter already had vivid activities in different venues in the district and will have AASTRO Clubs and other ventures in Schools and Colleges when it reopens.For cordinating any kind of activities or programmes ,one can contact AASTRO Wayanad District point of contact  Shri  M M Tomy.Ph :+91-9446176826.

Other point of contacts :

Shri K T Sreevalsan,Kalpetta,Ph : 9388098612

Shri.K P Elias,Kolagappara,Ph : 9447797115, 04936222335

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Jupiter loses a stripe

May 13, 2010 10:32 PM ⋅ Leave a Comment ⋅

Jupiter has lost one of its prominent stripes, leaving its southern half looking unusually blank. Scientists are not sure what triggered the disappearance of the band.Jupiter's appearance is usually dominated by two dark bands in its atmosphere – one in the northern hemisphere and one in the southern hemisphere.But recent images taken by amateur astronomers show that the southern band – called the south equatorial belt – has disappeared.The band was present at the end of 2009, right before Jupiter moved too close to the sun in the sky to be observed from Earth. When the planet emerged from the sun's glare again in early April, its south equatorial belt was nowhere to be seen.

This is not the first time the south equatorial belt has disappeared. It was absent in 1973 when NASA's Pioneer 10 spacecraft took the first closeup images of the planet and also temporarily vanished in the early 1990s.The bands may normally appear dark simply because pale, high-altitude clouds prevalent in other regions of the planet are missing there, revealing darker clouds below.

The belts are composed of ammonia ice, with a little sulfur and phosphorus thrown in. Scientists aren't quite sure how to account for them - one theory is that they are simply gaps in higher, paler clouds that allow the darker, deeper levels to show through.

It's not the first time the belt has disappeared - indeed, it happens every three to fifteen years. it last went missing in the early 1990s, and before that in 1973.This time, though, the disappearance happened as the planet spent a three-month period behind the sun, so that on its emergence the transformation appears rather more sudden.Over the next few months, we can expect to see a white spot appear which will gradually get stretched out by the planet's 350mph winds to form a new SEB.

check out more of  pictures here.

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Black Holes: Gas Blowers of the Universe

May 13, 2010 8:32 PM ⋅ 2 Comments ⋅

False colour image of the central region of a galaxy group in X-rays. The jet of matter blown out of the central black hole can be clearly identified by its radio luminosity (overlaid, purple-blue). (Credit: Max Planck Institute)

Supermassive black holes with the mass of many millions of stars have been detected at the centre of many large galaxies. A super-massive black hole acts like a lurking "monster" at the centre of the galaxy which swallows the surrounding material through the intensity of its gravitational pull. X-ray observations indicate that a large amount of energy is produced by the in-fall of matter into a black hole, and ejected in powerful jets. Astronomers from the Max Planck Institute for Extraterrestrial Physics,Germany, have now shown that these jets eject matter not only from their host galaxies but even the gas between the galaxy group members.

Astronomers have long been trying to understand how black holes interact with the environment , but to date the process is poorly understood. Observations and simulations have shown that active galaxies transport huge amounts of material with their jets, which are particularly luminous at radio wavelengths, into the intra-cluster gas. Signatures of this "radio-mode feedback" are observed both in radio and in X-rays.

Recent studies have shown that the amount of gas in galaxy groups, objects consisting of several galaxies bound together such as the Milky Way and the Andromeda Galaxy, does not add up to the amount predicted by cosmology -- unlike in galaxy clusters with up to thousands of individual members. Large amounts of mechanical energy injected into the gas from the central black hole may have removed part of it. However to date this was only a hypothesis. Previous group samples were limited to a handful of nearby objects populated by low luminosity radio black holes.

Using one of the largest samples of X-ray detected groups and clusters of galaxies identified by XMM-Newton together with radio observations, a team of astronomers at The Institute for Extraterrestrial Physics has studied the energetics of radio galaxy feedback in galaxy groups. In the COSMOS field, where almost 300 X-ray galaxy groups have been detected, the team has been able to show that the black hole activity in the centre of galaxy groups must have a dramatic effect on the surroundings: they eject sufficient energy to blow the intergalactic gas out of the gravitational well of the galaxy group. The mystery of the missing gas in galaxy groups is solved -- and the large impact of black holes in galaxy groups demonstrated for the first time.

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Don’t talk to aliens, warns Stephen Hawking

May 12, 2010 8:18 PM ⋅ 1 Comment ⋅

British physicist Stephen Hawking says aliens are out there, but it could be too dangerous for humans to interact with extraterrestrial life.

Hawking claims in a new documentary titled "Into the Universe With Stephen Hawking" that intelligent alien life forms almost certainly exist — but warns that communicating with them could be "too risky."

"We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet," Hawking said. "I imagine they might exist in massive ships ... having used up all the resources from their home planet. Such advanced aliens would perhaps become nomads, looking to conquer and colonize whatever planets they can reach.”

The 68-year-old scientist said a visit by extraterrestrials to Earth might well be like Christopher Columbus arriving in the Americas, "which didn't turn out very well for the Native Americans."

He speculated that most extraterrestrial life would be similar to microbes, or small animals. Microbial life might exist far beneath the Martian surface, where liquid water is thought to trickle through the rock. Marine creatures might also conceivably live in huge oceans of water beneath a miles-thick layer of ice on Europa, a moon of Jupiter.

But if a scientific census could be extended beyond our solar system to the rest of the Milky Way and beyond, the odds in favor of life's existence rise dramatically, Hawking said.

"To my mathematical brain, the numbers alone make thinking about aliens perfectly rational," he said. “The real challenge is to work out what aliens might actually be like."

Hawking said an attack by interstellar predators is just one of the dismaying possibilities in the search for intelligent life beyond Earth. Another possibility is that intelligence itself might be inimical to life. Hawking pointed out that humanity has put itself on the edge of its own destruction by creating nuclear bombs and other weapons of mass destruction.

"If the same holds for intelligent aliens, then they might not last long," he said. "Perhaps they all blow themselves up soon after they discover that E=mc2. If civilizations take billions of years to evolve, only to vanish virtually overnight, then sadly we've next to no chance of hearing from them."

Hawking has become one of the world's best-known scientists — not just because of his theoretical work on cosmology and black holes, but also because he has achieved so much while coping with a paralyzing neural disease for most of his life. In recent years he has become a prominent advocate for space travel, contending that humans must journey into the heavens and going through zero-gravity training himself.

This report includes information from The Associated Press and msnbc.com.

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Trivandrum Chapter Meet on 13th May

May 10, 2010 2:56 PM ⋅ Leave a Comment ⋅

AASTRO Thiruvananthapuram Chapter will have a meet on Thursday,13th may at Kerala State Science & Technology Museum and Priyadarshini Planetarium,PMG junction.AASTRO President Prof.K.Pappootty will preside the meeting and Planetarium director Shri.Arun Jerald Prakash and other eminent personalities will make their presence.upcoming and ongoing activities and programmes will be reviewed and plans for school & college activities will be shaped on the course.  AASTRO is planning to contribute for the Museum in vivid ways and this will be one of the mainstream agendas.All AASTRO members are requested to take part and more details are available with district point of contact Ph :+91-9846608238

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“Evolution of solar system” – Talk by Prof. Pappootty at Thrissur

May 9, 2010 8:43 PM ⋅ Leave a Comment ⋅

AASTRO Kerala Thrissur chapter inaugurated yesterday here by  by Prof K Pappootty  CMS Higher Secondary School, Thrissur on a  function  presided by eminent amateur astronomer and AASTRO Thrissur Chapter Chairman Shri.P R Chandramohan.District coordinator Shri.K S Sudheer gave the welcome address and Shri.Venugopalan delivered vote of thanks.Astronomy and science popularisation activists ,teachers,students and public from various parts of the district were participated in the programme.

Soon after the function there was an interactive session on Evolution of Solar System lead by Prof.Pappootty which nourished the audience.Vivid activities and programmes for AASTRO Thrissur chapter were planned in the meeting and responsibilities assigned for members to implement it. More details regarding are available with District point of contact;Ph :+91-9495576123

v s/AASTRO

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