A Wonderfully Scientific Science Fiction Film

Last night, thanks to the Wonderfest organization in San Francisco, I got a chance to see a science fiction film that was in theaters for so short a time that if you blinked, you probably missed it. It's called "Europa Report" and it is the story of a crewed expedition to Jupiter's intriguing moon Europa. This world, one of the four large moons of Jupiter discovered by Galileo, is an ice-covered ball that may well have a large liquid ocean under its surface.

You can see Europa's cracked surface on the picture I have posted above. (This is actually a montage of images from NASA's Galileo spacecraft, with additional image processing by Professor Ted Stryk to bring out more detail.) One possibility is that the dark cracks we see are places where material from deeper inside the Moon (perhaps even from the liquid ocean) is seeping up toward the surface.

In the movie (see the poster below), future astronauts (from a private space company) go to Europa to search for evidence of life. The complex story is told by interweaving the view from cameras in their suits and in their cabins, with footage they recorded for sending back to Earth and interviews with the mission controllers, who eventually lose contact with the ship. What the surviving astronauts eventually find is far more than the micro-organisms scientists currently hope might exist deep under the ice of Europa.

The film, by Ecuadorian director Sebastian Cordero, is now available on DVD and various internet film services. If you enjoy somewhat complicated but scientifically reasonable space stories, I commend it to your attention. If not, spend a little time Googling other images of Europa and check out one of the strangest worlds with which we have the pleasure of sharing the solar system.

Water Found on Largest Asteroid

Astronomers working with the Herschel space observatory have discovered water vapor coming from the largest asteroid in the asteroid belt, the one called Ceres (pronounced like "series"). By strict definition, Ceres is so big and round that it is no longer considered an asteroid, but is now designated dwarf planet number one (having been discovered on Jan. 1, 1801, long before Pluto).

Ceres is about 600 miles across and takes 4.6 years to orbit the Sun (Mars takes 1.9 years, while Jupiter takes 12 years.) The Hubble Space Telescope images of it (see one attached here) show lighter and darker areas. The water vapor is not evenly distributed around Ceres and there is more of it when Ceres is closer to the Sun, so there may be some ice that is sublimating (going from frozen form to vapor) in parts of Ceres.

At Ceres' distance from the Sun, ice on the surface would have all sublimated long ago, so this must be vapor coming from a deeper (frozen) layer, which was a surprise. Some astronomers think there may be enough water ice under the surface of Ceres to make an ocean. This is the first time water vapor has been detected in the asteroid belt, although we have seen it coming from a moon of Jupiter's and a moon of Saturn's. There may be plumes or "geysers" of water vapor coming from parts of Ceres, perhaps like the ones on Saturn's satellite Enceladus.

We will know a lot more about conditions on Ceres next March and April, when the Dawn spacecraft arrives for a rendezvous with Ceres and provides images with unprecedented detail of this intriguing member of our solar system. (Dawn gave us lots of great information about Vesta, the second largest asteroid, before it departed for Ceres in 2012.) Isn't it great how nature continues to surprise and delight us as we explore our cosmic neighborhood?

An Eerie Astronomical Photo

Click on the photo to make it bigger ^

Here is a gorgeous image taken by master astro-photographer Travis Rector (of the University of Alaska), showing a region of cosmic raw material (glowing gas and dark dust.) This is like one of those inkblot tests that psychologists are fond of -- what shape you see in the picture may be highly individual.

What we are actually looking at is a small part of a larger region where star birth is going on right now. Known by its catalog number of IC1396, this "emission nebula" is set to glow by the brilliant light of new stars that have already been born in this region and are shining with adolescent energy.

IC1396 is a cloud of loose gas and dark dust (the dust really isn't that different from what you find under your desk when you are too busy thinking cosmic thoughts to clean up regularly.) The dust is shaped into long filaments, when the light of energetic stars pushes the less dense parts of the dust away from the stars (in this case, in the down direction on this photo.) Only the thickest regions of dust remain after a while, making long, dark tendrils like we see here.

IC 1396 is about 3000 light years away in the constellation of Cepheus. You can see the entire nebula (much larger than the small part seen in our photo) here:
http://apod.nasa.gov/apod/ap120805.html

So what did the dark shape remind YOU of?

Stars That Eat Planets for Lunch

In the last couple of weeks, astronomers have announced the discovery of two stars that show evidence of having eaten some of their own Earth-like planets. Today came the announcement of the discovery of a star with planets that is growing larger and larger and is going to be eating its inner planets in the next couple of hundred million years.

These kinds of star "cannibal activity" are not that rare and should not cause us undue distress. It's business as usual in the Milky Way Galaxy, but what's new is that we are getting direct evidence for activities that earlier we only predicted from theory.

The two stars that already finished their meal a long time ago are known by their catalog numbers, HD20781 and HD20782. These stars belong to the same star system, and formed from the same original cloud of cosmic raw materials. This is the first "binary star" system where astronomers have discovered planets around each star. One has two Neptune-sized planets close by, the other has a Jupiter-sized planet whose orbit is not a nice circle but a stretched oval-shape.

Astronomers took a look at what the two stars are made of -- something we can learn by looking at the details in the colors of light from them. Every different element leaves its own "fingerprints" in the colors of light. Because the two stars formed at the same time, from the same "cosmic womb," we have more information about what they were like at the beginning.

According to Trey Mack, of Vanderbilt University, a graduate student who did the detailed analysis, both stars show evidence of elements in their atmospheres that were most likely not there when the two stars formed. Instead they are tell-tale signs of the stars having eaten planets made of rock. One star seems to have eaten the equivalent of 20 Earths, while the other consumed "only" ten Earths earlier in its history.

Astronomers have thought for a while that big "bully" planets like Jupiter and Neptune can, under the right circumstances, move inward and force smaller planets (like our Earth) to approach their stars until they are consumed. We are fortunate that this did not happen in the case of our solar system, and the Earth has a stable, undisturbed orbit which has allowed this blog's readers to evolve here. But it's getting clearer and clearer that not all star system will have the same history as ours did.

The other work deals with an act of cannibalism that happens late in the life of a star. All stars, at some point, have a "life-crisis" when their first fuel for making energy is all used up and the star has to adjust by briefly swelling up into a red-colored giant. The news is that astronomers have discovered that one of the stars around which the Kepler space mission has found three planets is on its way toward this period of swelling up. The star is known as Kepler 56, and the way in which it has started to swell up is telling us that it will eventually swallow its two inner planets, leaving only its outermost planet as survivor.

The devastation will not occur until more than a hundred million years have gone by, so it's not an immediate tragedy. We have seen many stars that swell up like this, but none of them have been known to possess planets. Kepler 56's worlds are therefore the first planets known to be orbiting other stars whose doom we can now predict. (By the way, in case you are worried, our own Sun will also have such a crisis and will swell up. But this is not happening for another five or six billion years, so I am not ready yet to include this eventuality on my home insurance policy.)

The image, by the way, is an artist's impression of an Earth-like planet being torn apart and then "eaten" by a Sun-like star.

Astrology, Astronomy, and Jetology

Every once in a while, I am mistakenly introduced as an astrologer instead of an astronomer.  There's a big difference, as I am quick to point out.  Astrology is an ancient superstition, left over from thousands of years ago, when most people saw celestial objects as gods or symbols of the gods, and not as physical bodies whose characteristics our instruments can now explore.

When, in the 1980's, it was revealed that President Reagan's White House schedule was for years vetted by a San Francisco astrologer, I was interviewed by the media as a critic of astrology.  I tried to come up with an analogy that would make sense to the news media and the public for why scientists had a hard time believing in the idea that your personality or destiny would be governed by the location of the Sun, Moon, and planets in the sky at the moment of your birth. I suggested a new form of "cosmic wisdom" called JETOLOGY, where your personality or fate could be explained by the position of all the jumbo jets at the time you were born. When people sniggered at the notion of jetology, I could then ask why astrology sounds any better.

I am reminded of this because, for those of you who are in the San Francisco Bay Area, I am preparing to be one of the featured speakers at SkeptiCAL, a one-day conference Saturday, May 31 in Oakland, on how to confront claims of the paranormal or the "too good to be true" by using common sense skeptical thinking.  See: http://www.skepticalcon.com/

Years ago, I wrote a short "Astrology Defense Kit" for science-oriented people who meet astrology believers.  You can read it at: https://www.researchgate.net/publication/253783518_Your_Astrology_Defense_Kit?ev=prf_pub 

If you want to see a wonderful short video on how it can be that the vague pronouncements that make up most astrological readings are taken seriously, I recommend the following episode of "Trick of the Mind" by British magician and skeptic, Derren Brown: https://www.youtube.com/watch?v=haP7Ys9ocTk

Ah, skeptical thinking -- if we had more of it during our years of education, during political campaigns, or when we view advertisements, our country would be so much better off.

A Possible Sister Star that Formed with Our Sun

Astronomers now know that stars, like people, tend to be sociable. Stars are often born and hang out in groups -- double stars, triple stars, star associations, and star clusters.  Yet our Sun is a single star, surrounded only by its family of planets and moons, but no sibling star to keep it company.  Was it always this way?

In recent years, it's become clearer that our Sun could well have formed in a loose group of thousands of stars, when it first "clumped" out of the gas and dust (raw material) of the Galaxy some 5 billion years ago.  If our mother cluster was indeed just loosely held together by the mutual gravity of the stars, in all that time, the stars could have drifted apart -- as many families do in the busy course of life. 

So we have been on the lookout for the Sun's now far-away sisters. This past week, a team of astronomers, headed by Ivan Ramirez of the University of Texas, announced that they might have found our first long-lost sibling. 

There are perhaps as many as 400 billion stars in our Milky Way Galaxy.  How can we possibly find our sisters in that huge and anonymous crowd?  After all, there are no star birth certificates on file at county offices and no little tags that hang around a star's neck.  The search involved two factors: First they looked for stars that have the same chemical make-up as the Sun (they consist of the same proportion of elements) -- which you'd expect from stars born in the same"womb."  And then they searched for stars whose motion could be calculated backwards in time and would have placed them close to us 5 billion years ago. 

Sorting through 30 possible candidates identified by other groups of astronomers after painstaking work, Ramirez' group came up with exactly one star that fit all the criteria.  Called by its catalog number, HD 162826, it's 110 light years away now, in the constellation box called Hercules.  (See the map.)  It has 15 % more mass than the Sun, and so it is a little brighter and a little hotter than our star. (In astronomy jargon, it's a Type F star, while our Sun is Type G.)

It turns out that HD 162826 has been searched for planets for the last 15 years, and so far, no planets have turned up.  But the kind of search it has been subjected to can't find small (Earth-like) planets. So the we have a long way to go before we can decide it the star has a planetary system around it or not.

Future surveys, allowing us to analyze the make-up of fainter stars, could well turn up other family members out there.  For now, astronomers will keep a far closer eye on this one possible sister star and follow it as it goes about its life.  Who knows, one day, someone from there may just respond to the equivalent of a cosmic blog post.

A Cluster of Stars Thrown Out of Its Galaxy at 2 Million MPH

A team of astronomers has discovered the first cluster of stars that has been thrown out of another galaxy. Whatever threw this rich grouping of stars out of the galaxy known by its catalog number as M87, was able to accelerate it to a speed of some 2 million miles per hour. Kids, don't try this at home without adult supervision!

It just so happens that the star cluster is being thrown roughly in our direction, but since M87 is 54 million light years away, no one is worried. The cluster will just wind up in the space between galaxies, wandering like the lost ships of legend, never finding its home port again.

M87 is a huge galaxy of stars and clusters, almost a million light years in diameter (our Milky Way Galaxy is about 100,000 light years across, by comparison.) In addition to thousands of billions of stars, M87 contains an estimated 12,000 "globular clusters" -- tightly bound groups of roughly 100,000 stars each. Our home galaxy only has about 150 of these globular clusters, and we are a pretty good-sized galaxy as far as cosmic requirements are concerned. So M87 makes us look like a 90-lb weakling in comparison.

So how did a cluster with many thousands of stars get loose from the considerable gravity of a giant galaxy like M87? No one knows for sure, but here is the clever idea that discoverers of the high-speed cluster are suggesting. Giant galaxies like M87 get bigger by eating smaller neighbor galaxies for lunch. Occasionally, they even merge with a big galaxy, gently pulling in the other galaxy's stars and other "inhabitants." What if M87, in the distant past, swallowed a big galaxy with a giant black hole at the center?

Astronomer have recently found that all big galaxies have big black holes in their crowded cores. The bigger the galaxy, the bigger the central black hole, in general. So M87 probably had a big black hole and the other galaxy would have had a big black hole too. As the two galaxies merged, their two black holes, like boxers circling each other in the ring, could have begun to orbit around each other. (We have seen pairs of big black holes in other such systems, so this is not a wild idea at all.)

Now, along comes our victim globular cluster, which had some orbit around the center of M87 that might well have brought it a bit too close to the pair of black holes. When the black holes interacted with the cluster, their gravity might have played a "game of pool" with it. In pool (or billiards, for some of you), you often see one ball interacting with another and then causing a third ball to go shooting off into a distant pocket. When the two black holes and the cluster had their moment of gravitational interaction, the cluster could have been thrown out of the galaxy by the tremendous gravitational energy of the giant black holes.

Astronomers have seen superfast stars thrown out of galaxies, but this is our first instance of seeing a whole cluster of stars shooting out from its home galaxy. M87 is one of my favorite galaxies anyway, with many other signs of violence and inner turmoil. This makes it even more interesting. The accompanying image is an artist's attempt to show the cluster coming out of M87, which is correctly shown as a fuzzy rounded blob.

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On a personal note, I would like to dedicate today's post to the memory of my good friend and colleague, Alan Friedman, the former director of the New York Hall of Science, who passed away this weekend.  Alan and I taught weekend courses on Einstein together, wrote papers on interdisciplinary approaches to teaching astronomy and physics, and bemoaned the state of science education in the U.S. over many dinners.  Alan also helped chart the course of the Lawrence Hall of Science in Berkeley, the Parc de la Villette science museum outside of Paris, and dozens of other museums and science centers where his advice was frequently sought.  He leaves an emptiness in the universe that will be impossible to fill.