Saturday, May 21, 2016

Mars: Close and Easy to See (And Wet Long Ago)


Tonight, if you look southeast, you can see Mars as a bright red dot next to the full Moon. Mars is in one of its closer positions, about 48 million miles away. Mars is in what astronomers call "opposition" right now (which is not a term related to the Bernie and Hilary situation!)
When Mars is in opposition, it is on the opposite side of the Earth from the Sun. This means that when the Sun goes down, Mars comes up in our skies, and Mars will be up all night long. (Looking at our diagram from Sky & Telescope magazine, you should also be able to find Saturn this evening or tomorrow night, lower toward the horizon than Mars.)
In recent weeks, even more evidence has been accumulating that ancient Mars, billions of years ago, had a much thicker atmosphere and water was therefore liquid on its surface. Astronomers now believe that there were once lakes and even perhaps seas on the red planet. Recently, planetary scientists even found what seems like evidence of two episodes of tsunamis that happened on Mars a long time ago, when a big chunk of rock or ice from space hit a larger body of water.
For details of this investigation, see: http://www.psi.edu/news/marstsunami
(Also check out a great new Hubble image of Mars at:
http://www.spacetelescope.org/news/heic1609/ )

Sunday, May 1, 2016

Special Opportunity to Support the SETI Institute


Some of my regular readers know that for years, I have had the privilege of serving on the Board of Trustees of the SETI Institute, a non-profit organization devoted to the search for life in the solar system and in the universe at large.
As a non-profit organization, the Institute depends on scientific research grants and on donations from members of the public who value its work. This coming week, the Institute is participating in the 2016 Silicon Valley Gives campaign and looking for 500 new donors and friends who want to help underwrite its work -- and be part of the quest to find life elsewhere. We Trustees have provided a $17,000 matching grant – to double any contribution you care to make.
You can be part of the campaign at:https://svgives.razoo.com/us/story/Seti-Institute-2
What kind of projects does the Institute do? You may have heard of the Allen Telescope Array (see the image), a connected group of radio dishes that scans the skies, hoping to eavesdrop on radio signals from an alien civilizations. But Institute’s 80 scientists are also involved with the search for planets orbiting other stars using the Kepler space telescope; with the search for water in the solar system, including on Mars and Jupiter’s moon Europa; with the exploration of Pluto (the Institute’s Mark Showalter discovered two of Pluto’s moons) and other worlds; and much more.
In addition, the Institute’s weekly syndicated show “Big Picture Science” brings humorous, accessible news about scientific ideas and discoveries on radio stations around the country and around the Internet. The Institute has frequent outreach activities in Silicon Valley and beyond. (You can see me explain black holes in six minutes at one of these at:https://www.youtube.com/watch?v=7DX_cc-IjpY )
So won’t you join me in becoming part of the team that works to answer the ancient and beguiling question, “Are we alone in the universe?”
Donations of any size are gratefully accepted at:https://svgives.razoo.com/us/story/Seti-Institute-2

Monday, April 11, 2016

Supersized Black Hole in an Unlikely Location
Astronomers have announced the discovery of a black hole that has “eaten” as much material as 17 billion Suns. A few such gargantuan black holes have been found elsewhere; what makes this one special is that it was found in a poor neighborhood, astronomically speaking.
Black holes are places where matter is so compressed, that nothing – not even light – can escape the grip of gravity. They frequently start life as the collapsed corpse of a massive star, but, under the right circumstances, they can really grow. If a black hole is frequently presented with “food” – matter it can swallow within its tight boundary – that boundary can grow. In a busy region, where lots of material is available, such as the crowded center of a big galaxy, black holes can grow until they contain millions of stars.
Many good-sized galaxies thus contain a “super-massive black hole” at their centers. Our Milky Way Galaxy has such a monster at its heart, which has swallowed enough matter to make 4 million Suns. But that’s still a long way from the super-sized black hole we just found.
Today we also know that galaxies like ours grow over time by swallowing smaller galaxy neighbors, in a process we call galactic cannibalism. If some parts of the victim galaxy are directed toward the giant black hole at the center of the cannibal, it can get swallowed by the giant black hole and help it to grow. (Some of us are reminded by this process of what’s been happening to banks in the U.S., where the largest banks and financial institutions have been swallowing smaller local banks whenever they can.)
At the centers of galaxies that live in a rich neighborhood – filled with other small galaxies they can be thinking about for lunch – giant black holes can grow to be “super-sized.” But in poor neighborhoods, there aren’t that many galaxies to munch on, and we thought black holes at the center of a galaxy would be limited in whether it could grow supersized.
The new discovery, made by a team headed by Berkeley professor Chung-Pei Ma, found the super-sized black hole in a galaxy known by its catalog number, NGC 1600. To our surprise, it resides in a poor neighborhood with only about 20 galaxies hanging out together. How it grew to be one of the largest black holes we know without many victim galaxies around it is still a mystery.
The monstrous black hole is located about 200 million light years from Earth, so that it poses no danger to our own neighborhood and will not interfere with continuing the presidential primaries or other local events. Understanding black holes and their role in the development of galaxies is high on the agenda of astronomers and in NGC 1600 they have a puzzling detail that doesn’t quite fit the standard story line.
For more on how astronomers discover such giant black holes, you can watch the non-technical lecture Chung-Pei Ma gave in the Silicon Valley Astronomy Lectures (that I have the pleasure of moderating) at:https://www.youtube.com/watch?v=LN9oYjNKBm8

(By the way, our image is not real; it is a computer generated field, showing what such a black hole might look like if you could see it close up. We find such black holes by the disturbance or motion they cause in nearby stars.)

Saturday, March 12, 2016

The Longest Eclipse Ever Found

This past week there was a beautiful total eclipse of our Sun visible for a few minutes from Indonesia, so it’s a good time to be thinking about all kinds of eclipses. A team of astronomers from several universities recently reported the discovery of a star that is eclipsed for more than 3 years every 69 years. This is the record holder for eclipses anywhere in the universe so far!
What would eclipse a star for such a long period of time? It can’t be a moon, or a planet, or another star, since all of those are too small to cause an eclipse that lasts three and a half years. There must be something around the star that extends over a much larger area and gets in the way of its light as seen from Earth.
After a lot of careful investigation -- using both recent observations by professional and amateur astronomers, and images going back over the last century -- the team concluded that they were seeing two aging stars whirling around each other in 69 years. One of the stars has lost a good deal of its material as it aged, and this lost material now forms a huge disk or doughnut around the emaciated star. It is this large disk that gets in front of the other star and cuts out its light as seen from our viewing angle.
We have seen other systems where such disks cause long eclipses. The best known case is the star Epsilon Aurigae, whose eclipses last about 700 days and happen every 27 years. It too has been studied by large teams of astronomers to uncover its secrets. 
But our star (which has no name, only a long catalog number TYC-2505-672-1) is further away and its eclipses take much longer to repeat. The only way astronomers were able to figure out that it has a 69-year cycle is because they were able to consult a hundred-year repository of pictures of the sky that has been lovingly kept up at the Harvard College Observatory.  
Those old images, many of them made on glass plates back in the days of chemical photography, are a treasure for astronomers. They are now being “digitized” – made into digital images that can be scanned and tracked via computer.
So if astronomers want to know if something interesting (like our eclipse) might have happened to a star sometime in the last century, they can now look up on the Harvard images what that star has been doing all that time. As someone who has trouble throwing out old files or magazines, my heart leapt when I heard about how important the old records were to the discovery!
And how far does stripped star with its disk of dark material have to be from the other star to only have an eclipse every 69 years? Their separation must be more than 20 times the distance between the Earth and the Sun, roughly the distance between the Sun and Uranus.
(The image shows an artist's impression of the dark disk moving in front of a red giant star.)
*****
By the way, to see a nice animation of the dark eclipse spot from the Indonesia eclipse on Earth, go to: https://commons.wikimedia.org/wiki/Category:Solar_eclipse_of_2016_March_9#/media/File:An_EPIC_Eclipse.gif

Sunday, January 31, 2016

An "All-American" Eclipse of the Sun Next Year


On August 21, 2017, there will be a gorgeous total eclipse of the Sun visible from the U.S. (and only the US!) The path of what is being called the “All American” total eclipse is only about 60 miles wide and goes from a beach in Oregon to a beach in South Carolina, crossing the country diagonally. (None of our country's largest cities will see it, alas.) A less spectacular partial eclipse will be visible to 500 million people in the other parts of the US and North America.

Astronomers expect tremendous media and public interest in the eclipse and it is not too early to start thinking about how and where best to see it. Eclipse enthusiasts are already busy reserving lodging and viewing space in the narrow region where the total phase can be seen.
The non-profit National Science Teachers Association (NSTA) is making available a popular-level introduction to help explain the eclipse and how to view it. The free 8-page booklet, which I helped write, is available at:http://www.nsta.org/…/f…/solarscience/SolarScienceInsert.pdf
Feel free to share this free booklet with anyone who might be interested.
The eclipse information comes from a new book for educators, entitled Solar Science, which I had the pleasure of writing with my long-time colleague and friend Dennis Schatz. It includes 45 hands-on learning experiences (and lots of background information) about the Sun, the Moon, the sky, the calendar, the seasons, and eclipses. You can see the full table of contents and some sample activities at:http://static.nsta.org/files/PB403Xweb.pdf
Shameless shopping hint: The book could be a wonderful gift for a teacher, a museum or nature center educator, a park ranger, or an amateur astronomer interested in public outreach. See:http://www.nsta.org/store/product_detail.aspx…
But quite separate from the book, please enjoy the free booklet, and, if you can, think about getting to the total eclipse path as part of your summer planning for next year. The image below, by French photographer Luc Viatour, gives you just a taste of how spectacular a total eclipse can be:


NASA is also planning activities and a national website for the eclipse, as is the American Astronomical Society, the main professional organization of astronomers.  I'll let people know when such other resources are available.  In the meantime, the free booklet from NSTA has an eclipse map and information about what will be visible when from many parts of the U.S.  At the end, there are links to sites where you can see very detailed maps of the eclipse path and even commentary about typical August weather at each place.

Wednesday, January 20, 2016

There is a Possible Super Earth in the Outer Solar System


Out there, way beyond the Sun's family, astronomers have discovered thousands of planets orbiting other stars. Among these alien planets, we have discovered a significant number of "Super Earths" -- planets more massive than our Earth but less massive than the smallest giants in our solar system, Uranus and Neptune. Our solar system has no such Super Earths, but many other systems do; they may be quite common.
Now, Michael Brown and Konstantin Batygin at Caltech, propose that we might just have a Super Earth in our solar system, but so far from the Sun, it takes between 10,000 and 20,000 years to make one orbit! (Pluto, for comparison, takes about 250 years.)
Brown and Batygin have been examining the orbits of icy chunks way beyond Pluto, in the region we call the Kuiper Belt. There are several chunks out there, including one Brown discovered in 2003, called Sedna, that move in an oddly aligned way. After testing many computer models to explain their odd orbit, their best model indicates there could be a planet 10 times the mass of our own Earth, whose stronger gravity is affecting the motions of many objects out where it orbits. Just a few of the affected chunks have been discovered so far and the planet itself has NOT be seen.
So this is a somewhat daring hypothesis, which the two astronomers explain in this brief video: https://www.youtube.com/watch?v=6poHQ2h00ZA
Please note that our image is a painting that Caltech commissioned. No one knows what this Planet Nine looks like.
Now here is the human side of the story. Michael Brown led the team that discovered Eris, the dwarf planet that is the same size as Pluto, in 2005. When he discovered it, he told his wife that he had just discovered a tenth planet and she had made a good decision in marrying him. Alas, instead of being acknowledged as the 10th planet, Eris caused astronomers to rethink the status of Pluto, and remove it from being the 9th planet. Brown was gracious about it, but you can imagine how disappointing it all was for him.
So now Brown may have "discovered" (or at least predicted) a real new planet. He is already nicknaming it "Planet Nine" and it's so big, no one will be able to call it a dwarf! If it is confirmed one day, he can go back to his wife and tell her, "Well, maybe I only discovered a dwarf planet before, but now I have discovered a real planet at last." Not a bad thing to discuss over dinner!
You can see a video where Brown discusses his role in the Pluto and Eris story at: https://www.youtube.com/watch?v=7pbj_llmiMg


Brown and Batygin

Thursday, December 31, 2015

Pluto Stamps to Debut in 2016


The U.S. Postal Service is going to release the set of two Pluto and New Horizons stamps in 2016 that you see pictured here. There has been an interesting connection between stamps and the Pluto mission.
In 1991, back when Pluto was still a planet, the U.S. issued a set of stamps showing close-up photos from space missions to all the planets except Pluto. The Pluto stamp was a drawing, and said "Not Yet Explored." This stamp so annoyed Alan Stern and and other astronomers who had been arguing for a Pluto mission, it gave them new energy to pressure NASA to approve a Pluto flight.
In 2006, just before New Horizons was launched, the scientists put one of those annoying stamps aboard the spacecraft and it was thus part of the mission that flew by Pluto last July. Having a U.S. stamp eventually leave the solar system amused the Postal Service people, and the new stamp of what Pluto actually looks like (with that nice heart shaped feature) is the happy result.
The Postal service is also planning to issue another set of stamps of the 8 planets (not including any pesky dwarfs this time) and a Star Trek commemorative series. See the full information at: https://www.nasa.gov/…/postal-service-honors-nasa-planetary…
Happy New Year to Fans of the Solar System and Stamp Collectors Everywhere! May your heart find fulfillment in the year ahead, just like Pluto's did..