Monday, January 27, 2014
Today, I just want to share a beautiful image with you. This view of planet Saturn, seen from above by the Cassini spacecraft was assembled from a variety of close-up images by computer programmer and amateur image processor Gordan Ugarkovic, but released by NASA because they were so pleased with the result.
Here we are looking down on the North Pole of Saturn in October 2013 (the weird weather feature called the "Hexagon" is faintly visible around the pole.) Such a perspective is not possible from Earth, but only from a spacecraft like Cassini.
The Sun is off to the left in this picture, and we see the planet casting a dark shadow on its own rings. The bands of "stormy weather" at different latitudes are also visible. Saturn is a planet made mainly of gas and liquid. If you were to try to "land" on Saturn, you wouldn't -- you'd just sink in and in.
You can see Saturn's main ring system surrounding the planet's equator. To give you a sense of scale, if we were to put Saturn down next to the Earth, the ring system would stretch almost from the Earth to the Moon. Click on the photo to see it bigger and enjoy!
You can see more of Gordan's home processed Saturn photos at:http://www.flickr.com/photos/ugordan/sets/72157594305165539/
Saturday, January 25, 2014
The big news from the world of astronomy is that a star has blown itself to pieces in a galaxy not so far, far away. The galaxy has the catalog number M82, and is only between 11 and 12 million light years away. (The nearest independent galaxy is a bit more than 2 million light years away, so, as galaxies go, M82 is one of our neighbors.)
M82 is located in the constellation of Ursa Major (the Big Bear), the same constellation that contains the well-known star pattern called the "Big Dipper." That means it is an easy target for telescopes in the Northern Hemisphere of our planet right now. Both amateur and professional astronomers are glued to their instruments, viewing and analyzing this doomed star.
Our color image, which shows the explosion -- called a supernova -- with an arrow, is from the Katzman Automatic Imagining Telescope at the Lick Observatory near San Jose (It was sent to me by Berkeley astronomer Alex Filippenko, who leads the project to discover exploding stars with this telescope.)
Astronomers are looking at the spectrum (the many different colors of light) from the exploding star. They have already discovered that this is that special kind of supernova which helped astronomers discover that the expansion of the entire universe is speeding up -- and earned them the 2011 Nobel Prize in physics.
Called a Type Ia supernova, this kind of explosion comes when a star corpse called a white dwarf is briefly re-ignited by sucking material from a close neighbor star (don't make any zombie jokes, please.) The energies involved when the white dwarf is overloaded with hot new material and blows up are so great that there is no earthly counterpart to compare them to. We are already seeing material blasting away from the explosion at speeds of 45 million miles per hour!!!
Since these supernovae are so important for understanding the universe (not just its expansion, but also its extent and how the death of old stars leads to the birth of the next generation), we are always grateful to have a nearby example to study.
If you have a telescope and want more information on how to find the galaxy and what equipment you will need to observe the supernova, see the Supernova 2014J pages at the website of Sky & Telescope magazine:http://www.skyandtelescope.com/observing/highlights/Bright-Supernova-in-M82-241477661.html
Monday, January 20, 2014
This past week brought us news of the death of two very different members of the astronomical community who became known for thinking far “outside the box” – astronomer Halton “Chip” Arp and amateur astronomer and telescope designer John Dobson. I got to know both of them through my work with the Astronomical Society of the Pacific (ASP.)
Chip Arp, trained at Harvard and Caltech, was an astronomer at the Hale Observatories who specialized in the study of the great islands of stars we call galaxies. He was particularly interested in those galaxies that had an unusual appearance or characteristics, and, in 1966, he put together a collection of images of over 300 of these, which he called his “Atlas of Peculiar Galaxies.” At the time, they seemed mysterious, but today we understand that many of them look odd because two or more galaxies have collided or passed too close (or are in the process of doing so). Such collisions are now known to be far more common among galaxies than astronomers first thought.
Alas, at one point in his research, Arp decided that the way we measure distances to galaxies (Hubble’s rule that the faster the galaxy is moving away from us, the farther it is from us) was not always correct. He thought he saw several pairs of galaxies that were moving at different speeds, and thus should be separated by vast distances, but seemed on his photos to be physically connected – a contradiction. Eventually, he decided that these connections challenged the notion that our universe is expanding smoothly from a “big bang” beginning. When other astronomers investigated his best cases with better instruments, he turned out to be wrong -- many of his “connections” were really just chance alignments of different objects on early photographs.
As few other astronomers joined him in his ultimately quixotic attempt to undercut the big bang idea, he slowly became embittered and felt persecuted. But I knew him back when he was Vice-President and then President of the ASP from 1979 to 1983 (and I was the Society’s Executive Director). Having been a champion fencer and a bon vivant, he cut a dramatic figure, arguing with genially with Board member Allan Sandage, charming our donors and members, and still full of energy in fighting the “establishment.” Although he turned out to be wrong, Arp was a useful figure in making astronomers re-measure and re-check their assumptions about galaxies and the universe. Science always needs a few well-trained “trouble-makers” and “dissenters” to keep us from taking our “party-line” views for granted.
John Dobson, on the other hand, was mostly self-taught in astronomy, but invented a new way of building amateur telescopes that helped make astronomy as a hobby more accessible. Today, many serious amateur astronomers build or buy telescopes with “Dobsonian mounts.” (His original inspiration, developed while being trained as a monk in a Vedanta Monastery, was to find a way to build telescopes cheaply for those who could not afford them. His first mirrors were made from the glass of discarded ship portholes.)
After he left the Monastery, he founded the San Francisco Sidewalk Astronomers, whose mission was to show the public the night sky by bringing telescopes to the streets. The sidewalk astronomy movement spread to other cities, and has influenced many amateur astronomy clubs to hold public events in settings where there may be more light, but there are also significant crowds of people who have never looked through a telescope.
Unfortunately, along the way, Dobson decided that both Einstein’s and Hubble’s work was wrong and that our modern view of the universe was fatally flawed. Instead of restricting his dynamic lectures and workshops to helping amateurs and the public appreciate astronomy (a subject where he excelled), he could not resist offering seminars on abstract issues in the science of the universe (where he had no particular expertise.) I remember one meeting of the ASP, where noted astronomer Margaret Burbidge sat for a long time with John Dobson, patiently explaining to him where his views collided with known facts about the universe – but no avail. I too tried in a small way to help him understand the power of Einstein’s theories, but he was by then too enmeshed in his own views to see clearly.
Still, we can celebrate that many, many thousands of people owe their exposure to astronomy to Dobson’s enthusiasm, and that there are several generations of California amateur astronomers who were inspired and helped by Dobson’s unfailing enthusiasm for sharing the sky. They continue to do “sidewalk astronomy” and to make new friends for our science.
The illustration above shows entry number 142 in Arp’s catalog, seen not in black and white, but with the full power of the Hubble Space Telescope. The two colliding galaxies have influenced each other’s structure (and just happen right now to resemble a penguin standing guard over an egg.) For more, see the short video at: http://www.spacetelescope.org/videos/heic1311a/
Below is a snapshot I took of Chip Arp during his time as ASP President.
Sunday, January 12, 2014
I'll share a little secret with you. If you follow astronomy developments, you might have noticed that there are a lot of news stories that come out at the beginning of January. The reason is that the nation's professional astronomers have their big meeting each year in early January, and many universities and observatories save up their big announcements to coincide with a talk or paper being delivered at that meeting.
This year was no exception -- many thousands of astronomers gathered for the winter meeting of the American Astronomical Society in National Harbor, a shopping-center-ambiance convention center (and tourist trap,) a short distance from Washington, DC. I was only there at the beginning, leading a workshop on education for young astronomers, because I had to get back for the start of the winter quarter at Foothill College. But the cosmic news stories were descending on us thicker than the snow in the northeast in the same week.
Here are just a few of the "stellar" news items from the week:
* The Kepler mission (searching for planets orbiting other stars) announced the confirmation of several dozen planets among the thousands first glimpsed with Kepler. Among them were five rocky planets bigger than Earth. Two of them are 40% bigger than our planet and have densities similar to lead!
* Scientists working with the Spitzer Space Telescope -- which views the universe of heat rays (infra-red) and not light -- made observations of brown dwarfs (failed stars). They found that many of them have huge storms in their atmospheres (like the giant storm on Jupiter we call the "Great Red Spot.") The stormy atmospheres of these stars is what the artist's impression in the accompanying image tries to show. Such storms probably have giant lightning bolts and torrential rain. But it's too hot for the rain to be water, so the droplets could hot sand, molten iron, or salts. Bring a strong umbrella if you go.
* A graduate student at Vanderbilt University has discovered what appear to be ordinary stars that have been kicked out of our Galaxy at speeds of a million miles per hour. Such "hyper-velocity stars" have been found before, but they were thought to be a special category of big blue stars kicked out by unfortunate encounters with the monster black hole at the center of the Milky Way Galaxy. The ones in the current study come from the direction of the main disc of our pinwheel shaped galaxy, not from the the center. So what could have given them such enormous speeds is a complete mystery.
I will tell you about other discoveries in future posts. In the meantime, if you have some science background and want to see what it feels like to be a science reporter at one of these meetings, you can go to the page where the Society archives the press conferences:
and check out one or two of them. Or just take a minute and contemplate how really alien and strange the worlds beyond our planet are turning out to be.
Wednesday, January 8, 2014
An international team of astronomers has just reported the discovery of one of the weirdest star systems we have ever seen -- a triple system of star corpses (dead stars) whirling around each other in a space smaller than the Earth's orbit around the Sun.
The system of stars is more than 4,000 light years away, in the constellation of Taurus. (But this story is no bull!) The system doesn't have a name, only a catalog number. It consists of one "neutron star" (which pulses with radio waves) and two "white dwarfs." Generally, a tiny "neutron star" only forms after a massive star dies by blowing itself to pieces, leaving a very compressed remnant (or "corpse") behind. So, those three stars, which show evidence of having formed together, had to remain together even when the biggest star of the three exploded. Later, the two smaller stars died and also became compressed objects (not much bigger than a planet) called "white dwarfs." (They get that name because they are small and white hot.)
Now the three corpses continue to spiral around each other, in a strange cosmic ballet . The heaviest corpse, the "neutron star" is really dense -- it is so compressed that to make something like it on Earth, we would have to take all the people in the world and squeeze them into a raindrop! (Then we would have one rain-drop sized piece of the neutron star.)
Sometimes we see such "neutron stars" giving off spinning magnetic beams of radio waves. Whenever such a radio beam sweeps over the Earth, we get a pulse of radio waves. In such cases, we also call these dead stars "pulsars." Their beams of energy can be timed with great accuracy.
In 1974, my former college advisor, Joseph Taylor (and Russell Hulse,) discovered the first pulsar in a double star system. Measuring its pulses enabled them to verify important predictions of Einstein's General Theory of Relativity, and earned them the 1993 Nobel Prize in Physics. At the time, astronomers thought that finding a neutron star/pulsar with a companion was pretty surprising (although today other double systems are known.)
Now suddenly, we have a neutron star/pulsar with TWO companions. How completely and wonderfully weird! And this particular neutron star spins hundreds of times per second. Its fast spin and two companions will allow astronomers to measure the predictions of Einstein's theories even more precisely than we have been able to do in the past.
Wednesday, January 1, 2014
Happy next orbit around the Sun, everyone. The center of our beautiful new year photo shows a Hubble image of an old star that is going through a little bit of a crisis in its life (as older stars -- and people -- tend to do.) The star, called RS Puppis, is getting brighter and dimmer on a regular cycle every 41 days. Stars that become changeable like this for a short part of their lives are called "Cepheid Variable Stars."
RS Puppis is one of the brightest known Cepheids, shining on average 15,000 times brighter than the Sun. It contains about 10 times more material than our Sun, and is 200 times larger in extent (an earlier part of its life crisis was swelling up to be much bigger than stars usually are.)
Because this star is surrounded by a cocoon of dust, the changing light from it is seen reflected from the dusty shells around it. (By the way, the cross of light you see coming from the main star and others in the picture is not real -- it is called a "diffraction spike" and is light sneaking around the support structure of one of the mirrors in the Hubble telescope.)
Cepheid variable stars are an important category of stars in astronomy. Their variations allow us to measure their distances and they are a cornerstone of how we know how far away things are in the universe. About 100 years ago, Henrietta Leavitt, a low-paid "computer" working at the Harvard College Observatory found the crucial relationship that allowed Cepheids to be used for this purpose. Even though women were not usually acknowledged for the "behind-the-scenes" work they did at the Observatory, this discovery was so important it was hard to deny her credit.
Playwright Lauren Gunderson has written a play about Henrietta Leavitt called "Silent Sky." It is coming to the Mountain View (CA) Center for the Performing Arts in January and February, for those readers who live in the San Francisco Bay Area. For everyone else, you can see a short excerpt from a previous production at:http://www.youtube.com/watch?v=KiwG6r-9gcw
Happy new year and may your skies be dark and clear in 2014.
P.S. For more on Henrietta Leavitt and contributions by other women to astronomy, see my resource guide: http://www.astrosociety.org/education/astronomy-resource-guides/women-in-astronomy-an-introductory-resource-guide/