Wednesday, April 29, 2015

First Movies of Pluto (Not Much Detail, But Still Amazing to Have)

Scientists working with the New Horizons spacecraft, which is scheduled to reach Pluto in July, released the first ever long-distance movies of Pluto and its giant moon Charon today.

The spacecraft was between 69 and 64 million miles away from Pluto when the images were taken, still roughly 3/4 of the distance between the Earth and the Sun. So these movies are very crude compared to what we will have soon.

Still, to have any real detail at all in our views of Pluto and Charon is wonderful and just whets our appetites for what's coming, as we get closer and closer to the famous dwarf planet that got so much public pity in the last few years. Discovered in 1930, it is (as the news release with the film says,) a cool mystery at the outskirts of the known solar system. But soon, thanks to NASA's long flight out there, we will know so much more about it. Stay tuned.

(If you click on the link, you will find two different perspective movies and some background information.)

Wednesday, April 22, 2015

The Search for Super-civilizations in the Cosmos

The WISE Telescope

In 1964, Russian scientist Nikolai Kardashev suggested that in the long history of the universe, which began billions of years before the origin of our Sun and Earth, really advanced civilizations might have developed.  Such civilizations might learn to control the total power of their stars -- and, ultimately, the total power of their galaxies. 

Now, Jason Wright and Roger Griffith, a pair of scientists at Penn State University, have actually searched for this last kind of super-civilization.  If such advanced beings have actually colonized and exploited the billions of stars within a galaxy, these civilizations could produce tremendous amounts of waste heat.  

Just like your car and your computer produce waste heat while they are operating, so the thought is that large-scale civilizations will generate an unnatural amount of heat, beyond the heat that all objects give off.

A recent satellite called the Widefield Infrared Survey Explorer (WISE) has been collecting information on sources of heat energy around the sky.  Wright and Griffith have looked at the output of 100,000 galaxies, to see if anyone of them might betray signs that the heat they produce is not natural, but comes from a super-civilization.

Although they did not find any obvious and definitive evidence, they did note some galaxies whose infrared energy was unusual in some ways.  These are worth investigating further. 

Of course no one really knows whether intelligent creatures can ever evolve to a level of technology where they take over an entire galaxy.  So finding one by this method is a long shot. (But I asked Geoff Marcy, the world's leading planet hunter, and he pointed out that just about all our searches for intelligence in the universe so far have been "long shots" -- no one can be sure today what method will pay off.  So Marcy feels we should explore as many different methods as possible.)

I also asked Jill Tarter, the U.S. leader of the search for extra-terrestrial intelligence using radio waves, and she also was excited about our adding more techniques to our SETI arsenal.  She told me she was adding the unusual galaxies from the WISE survey to the list of places where they would point radio telescopes, just in case there were any intelligent radio signals to be found.

Indeed, the SETI institute organized a Google hangout about this survey, and included Jill Tarter and Freeman Dyson, who first suggested ways that an advanced civilization might betray itself with infrared waves.  You can hang out and see what they said at:  

Sunday, April 12, 2015

A Monster Misses a Meal

There is a monster at the heart of our Milky Way Galaxy.  It's a super-massive black hole that has already eaten enough material to make 4 million stars like our Sun!  And, like all black holes, it is still hungry.  

For material to be "eaten" by a black hole, it must come quite close to the black hole "mouth" which astronomers call its event horizon.  Because black holes are the most compressed (squozen) objects in the universe, even overfed monster black holes have relatively small event horizons. Astronomers estimate that the one at the center of our Galaxy is 80 to 100 million miles across.  That's roughly the distance between the Earth and the Sun and is a tiny space in which to put 4 million(!) Suns.

So material near our black holes must come close to that tiny region to serve as food for the monster.  Things further away, like stars, can orbit around the black hole and not get swallowed.  (It is from the movement of such close, but not doomed, stars that we can estimate the gravity of the black hole.)

For the last few years, astronomers who monitor the center of our Galaxy have been predicting that a snack is on its way to the black hole.  A dusty cloud of material which they have nicknamed G2 was going to have a close encounter of the worst kind with the black hole in May 2014.  It was going to be torn apart by the enormous gravity of the monster and some of its material was then going to provide a meal for the black hole.  

When gas clouds (or other food) fall into a black hole, they are whirled around with unbelievable speed just before they fall in, and tend to glow briefly with x-rays and other forms of radiation before they disappear in the event horizon. However, no such flare-up of radiation was seen, even when the world's largest telescopes (like the Keck in Hawaii and the European Very Large Telescope in Chile). 

It appears G2 was not torn apart and consumed, because it wasn't a loose cloud of raw material, but a star with some of its birth material still around it.   The star managed to hold on to its "stuff" and make it away from the black hole, depriving it of a meal at this time.  Sorry, monster.   Better luck next time.

(In the picture, you see G2 in different colors going around the black hole (which is invisible, but whose position is marked by the plus sign.)  The blobs are shown at different times, and are red when G2 was moving away from us, and blue now that it was flung around the black hole and is coming toward us.)