March 31, 2011 at 11:22 am | 2 Comments
Exploring a Hot/Cold Little World
Yesterday was a banner day for the folks who run the MESSENGER mission to Mercury. The first images that the spacecraft has taken since it achieved orbit around the planet began streaming back to Earth. Now, there have been a good many flyby images of Mercury, not all of them high-res, since we began exploring the solar system in the mid-1960s with spacecraft. But, these are the first taken from a spacecraft orbiting the planet. This means that we’re going to (finally) get to see every bit of this world’s ancient, cracked and cratered surface.
The first images (which you can browse at the MESSENGER Web Site) are pretty detailed. For example, this Wide Angle Camera view shows an area near the north pole of the planet. It was taken as the spacecraft made its closest approach to the sunlit side of the surface. The long shadows are caused because the Sun is at an oblique angle to the spacecraft, which was just about to cross over into darkness.
The polar region of the planet is of great interest to astronomers because some radar studies of the area taken from Earth seem to imply that there might be ice on the walls of those craters. Sunlight never penetrates into the craters, so that would be an exciting cache to study someday. The water could be from impacts of comets, and studying THAT ice would tell us about the compositions of the comets that left their water behind.
The full imaging mission, which is planned to last for at least a year, begins on April 4; currently scientists and engineers are testing the spacecrafts systems and instruments to see how it is responding to its permanent home in orbit around Mercury — and enduring the harsh environment so close to the Sun.
Mercury might seem the last place you’d want to visit — and it probably won’t be the subject of human exploration for a long time. It’s a pretty extreme place, experiencing the widest surface temperature swings of any place in the solar system. It has little to no atmosphere, and its surface takes a radiation pounding from the Sun. Still, if you’re going to completely understand the solar system you inhabit, it pays to study the extreme places as well as the temperate (relatively) ones. In Mercury’s case, astronomers have a very specific set of questions to ask to help understand this place:
Why is Mercury so dense? What is its geologic history? What is the nature of its magnetic field? What is the structure of the planet’s core? What are the unusual materials seen at the poles? What volatiles (gases) are important at Mercury?
Some of these questions are those you’d ask at any planet to help you understand its composition and history. So, with Mercury, we’ll finally get some closure on the last of the major planets of the solar system. The only remaining world to visit (and there’s a spacecraft on the way) is dwarf planet Pluto. New Horizons will give it a swing-by in 2015, on its way out to explore the outer solar system. Another extreme, to be sure, but now we’ve got precedent with Mercury.
March 30, 2011 at 18:08 pm | 1 Comment
The Deaths of Stars
Stardeath produces some of the most intricate-looking objects in astronomy. If you have ever gone to the Hubble Space Telescope’s Web site and searched for planetary nebulae, you know what I mean. Giant stars produce giant explosions, like the long-known Crab Nebula.
This Hubble Space Telescope image shows us what the supernova remnant is made of (hydrogen gas, particles of heavier elements), and also shows us the structure of the nebula and how it’s influenced by the neutron star at the center. That neutron star is what’s left of the original star — a dense object spinning more than 30 times per second.
Stars like the Sun go a bit less violently, huffing off their atmospheres for millions of years before collapsing to make white dwarfs. The radiation from the central star continues to light up the remains of the former star, creating complicated visions of stellar death. The Eskimo Nebula (right), is a fine example of such a sun-like star’s death. The remains are called a planetary nebula, one of those odd misnomers in astronomy that has nothing to do with a planet, but is a nebula. This sunlike star began to die some 10,000 years ago, blowing bubbles of gas out away from itself and flinging its outer atmosphere to space. Our own Sun might look like this some billions of years from now.
Well, I’ve been long fascinated with the images of star death, ever since I wrote my first book (with Jack Brandt), about Hubble Space Telescope science (called Hubble Vision). A few years ago when I did an update of one of my more-popular planetarium shows, called Hubble Vision 2, I had a great selection of star death images to choose from to tell the story of stellar demise. I wrote about sun-like stars, “Hubble’s images of these stars in their death throes comprise a haunting gallery of destruction.”
As is always the case with my shows, I knew that the soundtrack artist (who also happens to be my husband and co-producer) would find a way to make the scene memorable with his trademark space music and video choreography. The scene in the show is a solemn, beautiful procession of planetary nebula images that bring home to audiences the majesty of a star’s passing.
Fast-forward a few years to this month, and Mark has now released the music from that show soundtrack in an album called Geodesium Stella Novus (where you can preview and buy the album if you’re interested). And, he created a music video based on that planetary nebula scene that really does bring home the majesty of that haunting gallery of destruction we first introduced in the show. We created a fulldome version of the music video, which you might get to see someday at your local digital planetarium.
But, we’ve also got a “flat-screen” version available on our Youtube channel for people to watch and I’ve embedded it below. The piece of music is called “Light Echoes”, and it accompanies these gorgeous views of star death, ranging from supernova remnants to planetary nebula, as cosmic art. It’s not a new concept — the universe as art. But, you have to admit, when you see the way nature has arranged the aftermath of stardeath, it can look evocative, haunting… and artistic!
March 29, 2011 at 10:47 am | Leave a Comment
Some Spacey Places to Surf
The Web presents some great places to see and learn about astronomy and space science. I have favorite places I go to, many of which are listed in my blogroll at the left. Here are a few of my current favorites.
First off is the Carnival of Space. It’s a wonderful melange of information and opinion about all things “spacey”. This week’s is hosted by the ever-erudite Paul Glister over at Centauri Dreams. As he says, the Carnival is a place “in which people wiht their eyes on the stars go to work to explain the latest findings.” Check it out!
Another daily stop is Phil Plait’s Bad Astronomy blog. Phil’s writing ranges from astronomy and space science to filtering out the “woo-woo” science that passes for “critical thinking” among practitioners of such arcane arts as astrology and mystical pseudo-medical practices. He also takes on fuzzy thinking among those who don’t quite understand science (like some of our less-learned politicians and media practitioners), as a professional skeptic. Reading Phil’s work is like giving your brain a ‘wash and brush’ — clearing out the cobwebs.
Media-wise, there are some good informational sites out there purveying science news. Of course, Science News comes to mind. We’re long-time subscribers to the print version. Sky & Telescope Magazine and online site are good “go to” places for astronomy information. So is Astronomy Magazine and web site. In the past couple of years, I’ve been doing some work for a unique online video magazine and news source called Astrocast.TV. We do night-sky tutorials, explorations of deep-space astronomy, cover newsworthy events in the burgeoning private space industry, and offer insights about Earth science. Universe Today offers daily insights into all kinds of science, written by journalists and scientists.
There are number of really good mission-based sites out there that I check out as often as I can. Hubblesite is one, featuring the latest and greatest from the Hubble Space Telescope. The European Southern Observatory is another — those guys are working scientific wonders in the mountains of Chile. Gemini Observatory regularly releases cool images from its telescopes in Hawai’i and Chile. The National Radio Astronomy Observatory gives us the radio view of the cosmos, while the Spitzer space Telescope folk share the infrared universe. Over at the x-ray end of the electromagnetic spectrum is the Chandra X-ray Observatory. If planets are your thing, then the Mars Mission Web page is a good start for all things Red Planet. The Cassini Solstice Mission pages offer frequent looks at the planet Saturn, where planetary scientists are continuing a years-long exploration via long distance. Close to the Sun, the Mercury MESSENGER mission is ramping up to give us a long-term closeup look at Mercury. The pictures should be coming later today (Tuesday, March 29) The Kepler page keeps us up to date on the latest planetary discoveries around other stars.
This is just a small taste of what’s out there if you want to explore the wealth of information we know about the cosmos. Happy surfing!
March 23, 2011 at 21:20 pm | 3 Comments
Musings on a Wednesday Night
There’s never a dull moment in astronomy. If you’re a skywatching addict, then there’s something for you every night to check out. Last Saturday it was the Full Moon, and it was gorgeous! We didn’t get to see it rise here at the hacienda, but after it cleared the mountain in back of us, the Moon looked great. Tonight is quite clear (and cold), and so maybe later on I’ll step out and check out the starry skies. Right now, Sirius is twinkling low in the southwest and the stars of the Winter Circle are setting soon. Another sign that spring is here for those of us in the Northern Hemisphere, and autumn has arrived for the folks in the Southern Hemisphere.
Mars isn’t in our night-time sky right now. In fact, it appears so close to the Sun that it’s nearly impossible to see without help. But, even though it’s out of sight, Mars is not out of mind. Even the leader of Venezuela has been talking about the Red Planet this week, tying capitalism to the loss of life on Mars. I’m not precisely aware of when Mr. Chavez got his degrees in planetary science OR economics and political science, and I’ve not seen evidence of his research contributions to those fields, but I’m reasonably certain that the lack of life on Mars isn’t due to a plot against Marxist-Leninist paradises here on Earth. It’s amusing to read his rhetoric, even as you see it for what it is — getting in a dig at his neighbors to the north. It seemed like an unlikely topic for him to bring up, but then again, any world leader talking about anything to do with the sky (astronomy or planetary science-wise) catches my attention.
No, Martian life — if it existed — probably never got started down the long evolutionary path that we did here on Earth. Conditions on the Red Planet became untenable for that — not due to Adam Smith-style capitalism, which is a human construct that came long after life took root on Earth. More likely physical conditions were to fault on Mars, entirely NATURAL conditions that existed long before life on Earth was able to do more than look up to the sky in wonder. Changing conditions (atmospheric loss, cooling, geological changes) may well have doomed anything more complex than a Martian microbe to a very uncertain future.
As it turns out, if a group of scientists at MIT in Cambridge, Massachusetts are right, there’s a tantalizing possibility that life on EARTH may have its seeds on Mars, descending from organisms that somehow made their way from Mars to our planet in the very distant past.
It’s not so far-fetched as it might sound at first. There are some well-established ideas about Mars that lend themselves to this story and make it a plausible avenue of research into the origins of life on Earth.
First, early in solar system history, the climates on Mars and the Earth were much more similar than they are now. Life that arose and flourished on one planet could presumably have survived on the other — if it could get from one place to the other. Second, an estimated one billion tons of rock have traveled from Mars to Earth since the two planets formed. That material was blasted loose by asteroid impacts and sent on its way between planets. Eventually, the “stuff” from Mars hit EArth. Third, microbes have been shown to be capable of surviving the initial shock of such an impact. So, if there WAS life on Mars (in handy microbe form, which is an easy way to transport living material), and it somehow caught a ride on an outbound rock, then given a good set of orbital conditions, there would have been NOTHING stopping that rock and its life-load from getting here eventually. When you look at the orbital dynamics of our two planets, it turns out that the chances are a hundred times better for rocks to travel from Mars to Earth.
I know that sounds surprising, but life is amazingly resilient, and in fact, there is evidence such microbes could also survive the thousands of years of transit through space before arriving at another planet.
So if life got started on Mars first, and it got blasted off the planet in a meteorite impact, then some hardy microbes could have been carried here to Earth. And, if that’s true, then Ray Bradbury’s final scene in “Martian Chronicles” is more prophetic than he may have thought when he wrote it back in 1950. But, instead of finding those humanoid Martians staring at their own faces in a canal on Mars, all we have to do is look in the mirror in our homes here on Earth.
Of course, there’s a lot of work to do to prove this hypothesis, but I find it kind of poetic and interesting. We — you, me, Mr. Chavez — all the people on Earth — really COULD be Martians, and here all along we’ve been yearning to explore that RedPlanet so far away. And, we’re using technology that is the fruit of the capitalism that Mr. Chavez regularly decries on TV, radio, and the Internet — ironically enough, media methods that also depend more on capitalist investment than he might feel comfortable with.
But there you go. Astronomy and planetary science lead one down some interesting paths, and not always scientific ones. I think it’s rather interesting that even though his politics aren’t the same as mine, Mr. Chavez has an awareness of Mars and its past and future. I wonder if he stargazes, too?
March 19, 2011 at 13:34 pm | Leave a Comment
Carnival of Space, That Is
This week’s Carnival of Space — that compendium of writing by various bloggers — is now up for your reading pleasure. Take a few moments to check out stories about everything from the Japan earthquake to cataclysmic variables, density waves in spiral galaxies, comet Halley, and movie reviews over at Steve’s Astro Corner.
As you’ve probably read (in breathless prose on some media sites, I’m sure), there’s a Full Moon today (March 19th). You’ve no doubt been treated to all this hype and anguish over how it’s the LARGEST FULL MOON EVAR!!! and the CLOSEST FULL MOON IN MODERN TIMES and all kinds of other hyperbolic fulminating.
Lots of people are crowing about something that isn’t all that rare… and didn’t cause the earthquakes, thank you very much.
Here’s a sanity check on the news behind the hype.
As it turns out, tonight’s Full Moon is going to be closer to us than usual, and for that reason, it’s being dubbed a “SuperMoon”. The last one THIS big was in 1993 (as you can read here at NASA’s Science News site).
But it’s not all that an unusual thing to happen. During parts of its orbit, the Moon does sometimes come closer to us than other times. As it happens, this is the closest one in less than three years. Yep, that’s right, the last “close” full Moon was in late 2008. In fact, the January 2010 Full Moon was only 20 kilometers farther away than tonight’s.
The point is, this big Full Moon that lots of mainstream media (and astrologers) are hyping isn’t so rare after all.
My fellow blogger Ian Musgrave in Adelaide, Australia, did a little nosing around to find out the truth behind the hype. He takes on some popular mythology about the Moon and all kinds of coincidental occurrences here on Earth. He also has a nice chart you can check out that shows the distances of the “close” Full Moons since 1991. There have been 21 in 20 years.
Umm… not so rare there, folks. But, that hasn’t stopped Yahoo.com, Accuweather, and other sites I used to think were credible from spouting nonsense that appears to be based on something an astrologer wrote. Do I need to point out (again) that an astrologer is not a scientist — not a lunar geologist, not an earth sciences person, not an astroNomer, and certainly not a credible expert on lunar orbits?
Look, think of the Full Moon in its orbit like a car going around an oval-shaped race course. If you stand at one end of the oval, the car is going to be close to you at least once each time it goes around. That’s called “perigee” and it’s entirely normal and nothing to start casting horoscopes over. When the car is farthest from you in the oval, it’s at apogee. Now, due to various conditions, sometimes the car gets closer to you during perigee than at other times during perigee. So, imagine that in one lap it was three meters away from you. In the next lap, it might be one centimeter closer to you. It’s perfectly normal and nothing to start reading palms about.
The Moon’s orbit is the same way, in that sometimes it’s a few percent closer to us than other times. Occasionally, that perigee time coincides with Full Moon — the phase of the Moon that occurs when the Moon is on the opposite side of Earth from the Sun, thus allowing the side facing us to be bathed in sunlight. (Perigee and Full Moon are two different things, so don’t confuse them with each other. For a more thorough discussion of Full Moon, go here. ) They are perfectly normal and nothing to start blaming the Japan earthquake on. That temblor and all the earthquakes that occur in Japan and around the Pacific Basin are due to the so-called “Ring of Fire” are due to Earth’s plate tectonics. These are natural phenomena and nothing to start blaming the Moon for.
I’m not sure why this is such a big deal, this SuperMoon thing. Is it because if an astrologer says so in flowery language that somehow looks impressive but means very little (the definition of amphigory, by the way)? If so, see the last sentence of previous paragraph. Is it because if you put the word “Super” in front of something, that makes it all magical somehow? It’s like putting “mega” in front of words. You see it all the time, particularly when somebody wants to sell you something (whether product or whack idea). “MEGA-SAVINGS ON BULK ADULT DIAPERS!” or “MEGA-SALE AT XXX AUTO DEALERSHIP!!!!! SAVE 1000′S OF $$$” (Try saying that last one out loud and it comes out as “Save one thousands of dollars!” Who talks like that? Who taught the copywriter how to punctuate?)
Now, you can take my word for it that there’s nothing magical or mysterious about the closeness of this particular Full Moon. It will look beautiful, provided you aren’t under cloudy skies. I guarantee you will (or have done so already) walk outside, look at this gorgeous Full Moon and say to yourself, “It’s wonderful, but I don’t see much difference from the other Full Moons I’ve seen.” And, you would be correct.
And, that’s the point. Last month’s Full Moon measured 33.4 arcseconds across. Tonight’s Full Moon will measure 33.7 arcseconds. It’s NOT a difference that you or me or anybody who looks at it with the old Mark I eyeballs are going to SEE. I defy you to tell me your eyes can discern that small of a difference. And furnish proof, if you do.
What I will CHALLENGE you to do is go out and look at the lovely Moon. Enjoy it. Cherish it. That’s what its’ all about in skygazing. Enjoy what you see. Any time you can step outside and enjoy a lovely moon rise is a life experience worth having!
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Copyright 2013, Carolyn Collins Petersen
Image of Horsehead Nebula: T.A.Rector (NOAO/AURA/NSF) and Hubble Heritage Team (STScI/AURA/NASA)
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