Sunday, October 26, 2014
Many of you in North America who saw the partial eclipse of the Sun last Thursday may have noticed a nice dark spot under the eclipsed part of the Sun. The full "active region" (that the visible spot is part of) is bigger in area than the giant planet Jupiter and has become the largest such feature on the Sun in 24 years.
With the kind permission of the photographers, I am posting here a beautiful close-up of the area, by Randall Shivak and Alan Friedman. Look how wonderfully complex it is!
The darker regions on the Sun are called sunspots; they look darker because they are slightly cooler than the Sun's visible surface layer. The Sun is made entirely of seething hot gas, where the atoms are so hot, they easily lose their electrons. This makes our Sun highly magnetic, and as it spins, its magnetic zones get all twisted up. It's those twisted regions that appear to us as active regions.
Astronomers have already observed some "flares" -- sudden releases of extra energy -- from this region, but they haven't been sent in our direction in space. The region is now facing the Earth as our Sun does its slow rotation. So we may get some extra high -energy particles coming our way in days to come (or not -- weather from the Sun is as hard to predict as weather on Earth.)
For a nice movie of this region "crackling" with magnetic energy as the Sun rotates, see: http://apod.nasa.gov/apod/ap141022.html
Wednesday, October 15, 2014
On Thursday afternoon, Oct. 23, there will be a partial eclipse of the Sun, visible from the U.S. Different amounts of the Sun's area will be covered by the Sun. (For example, 40% of the Sun will be covered from the San Francisco region.) I have put question-and-answer introductions to the eclipse at: http://www.astrosociety.org/society-news/2014-eclipse-fact-sheets/
You can consult the national sheet for the degree the Sun will be eclipsed in your area. Here's wishing everyone clear skies. And please remember, do NOT look at the Sun without proper protection. Follow the instructions on the sheets or go to an astronomy place (observatory, college, planetarium) near you to join an eclipse viewing session.
This Sunday, Oct. 19th, a comet will pass closer to Mars, than any comet has passed to the Earth in recorded history. Comet Siding Spring (named after the observatory where it was discovered) will pass within only 87,000 miles of Mars. An armada of telescopes near Mars and Earth will try to get a good glimpse of it. From its orbit, this appears to be what you might call a "virgin" comet, making its first entry to the inner solar system. It is coming from the distant reservoir of ancient "icy chunks" that surround our solar system in a giant cloud.
A comet is just such an icy chunk that comes close enough to the Sun so that the Sun's energy and wind begin to evaporate the ice and loosen the dust frozen inside it for billions of years. These comets thus contain some of the original material from which our solar system was formed some 5 billion years ago.
To learn more about NASA's plans for observing this Mars visitor, see: http://science.nasa.gov/science-news/science-at-nasa/2014/09oct_cometprep/
For a while, NASA scientists worried that dust from the comet may damage some of the spacecraft around Mars, but recent calculations are showing that the path the comet is taking means that its dust is not likely to pose a serious threat. But we'll see Sunday. Perhaps there will be faint "shooting stars" (dust burning up in the thin atmosphere) on Mars.
Sunday, October 5, 2014
In 2008, the BBC made a biopic (or dramatization) of events in Albert Einstein's and Arthur Eddington's life and work, and how they intersected. It was cosponsored by HBO and I just found out that HBO is currently showing this film (you can see it in the "On Demand" section of your cable TV offerings if you subscribe to HBO.) It may not last long, and it is not available on DVD yet in the U.S.
I recommend it with some enthusiasm (it's moving, and fun to watch), but also many reservations (the science and history are not always accurate, or -- to be charitable -- are twisted or changed in the interests of higher drama.)
I think everyone has heard of Einstein, but Arthur Eddington was an astronomer and physicist in England in the early part of the 20th century who contributed a lot to our understanding of how stars work. He was also a key member of the eclipse expedition in 1919 that tested if Einstein's crazy new theory of gravity, space, and time -- the general theory of relativity -- was correct. Measurements during that eclipse, and especially during a later eclipse made by a team from the Lick Observatory, established that Einstein was right and that the universe was more complex and beautiful in its inner workings than earlier scientists had imagined.
The film begins and ends around the eclipse expedition, but then goes back in time to set the scene. Many historical details are wrong or skipped over -- Elsa was divorced with two kids when she re-encountered Einstein in Berlin, the famous image of Einstein sticking out his tongue was later in his life, Eddington didn't have to tell Einstein about Mercury, etc. But such details don't matter to most viewers, and sometimes mixing things up a bit helps move the story along. And the flavor of the excitement around relativity is well characterized, with the two main actors doing a nice job in portraying the scientists and their personalities.
If you get HBO, or have a friend who does, and have a chance to see it, I recommend the film for everyone except historians of 20th century science, who will have a fit about those details. (The same production team also did a biopic about Stephen Hawking, called just "Hawking" and I gather you can find that film in segments on YouTube.)
Above you see the two scientists as portrayed in the movie, below you see the two of them from real life.
(For movie and TV fans, I can't resist adding: Gollum plays Einstein, Dr. Who plays Eddington.)