Astronomy
esiegel | May 28, 2010"You must live in the present, launch yourself on every wave, find your eternity in each moment. Fools stand on their island opportunities and look toward another land. There is no other land, there is no other life but this." -Henry David Thoreau
Maybe for you, Henry. But a century and a half later, we are explorers of many other lands, including this one.
Back in 2004, two rovers landed on Mars, Spirit and Opportunity. And while Spirit has gotten all the press with its trials and tribulations, Opportunity has quietly been, well, exceeding all reasonable expectations.
Opportunity landed in…
esiegel | May 27, 2010"Mortal as I am, I know that I am born for a day. But when I follow at my pleasure the serried multitude of the stars in their circular course, my feet no longer touch the Earth." -Ptolemy
When you look up at the stars in the night sky, perhaps the most striking thing that they do is rotate about either the North or South Pole, depending on which hemisphere you live in.
But what do you get if you look up at the same time each evening, night after night?
Well, unlike the planets Mars (in red) and Uranus (faint, to the upper right of Mars), the stars stay in the same exact spot from night to…
rallain | May 25, 2010I was at the zoo this weekend, it was fun but hot. Somewhere near the middle, there was a sun dial.
The cool thing (well, I think sun dials are cool anyway) was that the shadow was pointing about to the "12". I looked at my watch and it said 1:05 PM. What is up with that? The answer: Daylight Saving Time.
What does noon traditionally mean? In this day of the digital watch, most people associate noon with 12:00, you know - lunch time. But before clocks, noon referred to the time of day where the Sun was at the highest point in the sky. It is not too difficult to find this time. Just…
esiegel | May 24, 2010"Magic mirror on the wall, who's the fairest one of all?" -the Wicked Queen
For a galaxy, though, it's really not fair to ask which one's the fairest. It's simply too subjective of a question. But size, now that's something we can measure.
So, I ask you -- galaxies of the Universe -- to step forward and show yourselves! Galaxy, galaxy on the wall, who's the largest one of all?
Nice try, Andromeda. Our biggest sister, Andromeda, has about 400 billion stars that make her up. That's about 50% more than our Milky Way has, and it makes Andromeda the largest galaxy in our local group. Andromeda is…
esiegel | May 22, 2010"The moon's an arrant thief,
And her pale fire she snatches from the sun." -William Shakespeare
Let's assume you lived before we walked on the Moon. Before we had ever been to space, hell, even before the invention of the telescope. Why not go all the way back to before we knew the planets went around the Sun! You know, back when all you had to go on for knowledge of the sky was your eye.
Some nights, you look up at the sky, and what would you see? Instead of thousands and thousands of stars, something might be filling your sky with light pollution. Indeed, the closest astronomical body to…
rallain | May 20, 2010I am going to try to answer another Ask a ScienceBlogger question. This one is from George P. Burdell. He asks:
"If the universe is expanding from the big bang, has anyone tried to reverse plot the galaxies to figure out the exact point where the big bang occurred?"
Actually, he asked two questions, but I am just answering the first. Second, let me note that I am not really a cosmologist - so I am just making up answer.
In short, the answer is that everywhere is the center of the universe. Think of it this way. Imagine that there are only two dimensions and these two dimension are the…
esiegel | May 17, 2010"From the intrinsic evidence of his creation, the Great Architect of the Universe now begins to appear as a pure mathematician." -Sir James Jeans
Last time we met, I posed a mystery to you: why are globular clusters the smallest in the Universe?
And what's more than that, we never find them in isolation! We always find them bound to galaxies (or, if not bound to a galaxy, then within a cluster of galaxies; thanks Steinn), but never just off in deep space, floating on their own like some lone Death Star.
Like all structures in the Universe, everything we're talking about here -- stars,…
elerner | May 17, 2010Space has a way of inspiring the imagination more than almost any other scientific field. When we talk about making huge investments of money and brainpower to solve some looming problem--say, the need for renewable energy--we talk about making a new moon shot. And while some of the most exciting scientific discoveries are being made right now on the smallest scales imaginable, there is something about the grandness of both time and distance that makes space truly the final frontier.
Drawing out the comparisons between investigating the infinitesimal and the infinite, astronomy is the only…
esiegel | May 14, 2010"I may be an old lion, but if someone puts his hand in my mouth, I can still bite it off." -Wilhelm Steinitz
When you look at a typical galaxy, you usually find a disk, a bulge, and a few dots diffusely strewn about the exterior.
Like an old lion, these dots have been around for a very long time: often for longer than the galactic disk itself! Just what are these things? Well, we can learn a little more if we look in the X-ray (with Chandra) and the infrared (with Spitzer), in addition to a visible light image (from Hubble). Let's take a look at a composite:
Just what are these dots that…
drorzel | May 12, 2010Via Jennifer Ouellette on Twitter, I ran across a Discovery News story touting a recent arxiv preprint claiming to see variation in the fine-structure constant. It's a basically OK story, but garbles a few details, so I thought it would be worth giving it the ResearchBlogging treatment, in the now-traditional Q&A format.
What did they do? The paper looks at some spectral lines in radio emission from a moderately distant galaxy with the poetic name "PKS1413+135." These lines are produced by OH molecules in interstellar gas clouds, and the frequencies they see suggest that there may have…
esiegel | May 7, 2010"What is art but life upon the larger scale, the higher. When, graduating up in a spiral line of still expanding and ascending gyres, it pushes toward the intense significance of all things, hungry for the infinite?" -Elizabeth Barrett Browning
I don't mean to ask why the Milky Way is a spiral in an existential sort of way. You see, many galaxies, like our own, and also like Andromeda and the Triangulum Galaxy (below) -- our nearest galactic neighbors -- are spiral galaxies.
They're what I think of when I think of galaxies, and they're probably the first thing that pops into your head, too.…
esiegel | May 5, 2010It will shine still brighter when night is about you. May it be a light for you in dark places, when all other lights go out. -J.R.R. Tolkien
The night sky is no stranger to most of you. Once the Sun goes down in the west, the sky darkens, turning ever-deeper shades of blue until it approaches blackness, and stars and planets begin to come out against the fading backdrop.
Many things pollute the darkening sky, and can obscure your vision of the dimmest objects in the sky. Getting away from the city and light pollution is important, as is having clear skies without too many clouds in them.…
esiegel | May 3, 2010"An educational system isn't worth a great deal if it teaches young people how to make a living but doesn't teach them how to make a life." -Unknown
Every now and again, people with all sorts of backgrounds -- from some graduate school all the way to having not finished high school -- ask me about getting involved in Astronomy and Astrophysics. Often, people's interest simply come from looking up at night.
I'm not going to lie, this is a huge question, with many different answers. First off, let's start off assuming that you have no background in math, no background in physics, and that you'…
drorzel | May 3, 2010Voting has closed on the Laser Smackdown poll, with 772 people recording their opinion on the most amazing of the many things that have been done with lasers in the fifty years since the invention of the first working laser (see the Laserfest web site for more on the history and applications of lasers). The candidates in the traditional suspense-building reverse order:
Lunar laser ranging 22 votes
Cat toy/ dog toy/ laser light show 41 votes
Laser guide stars/ adaptive optics 46 votes
Holography 47 votes
Laser eye surgery 53 votes
Optical storage media (CD/DVD/Blu-Ray) 60 votes
Laser…
esiegel | April 28, 2010Perhaps in time the so-called Dark Ages will be thought of as including our own.
-Georg Lichtenberg
We've been going through the history of the Universe -- from inflation to the present day -- and you can read parts 1, 2, 3, 4, 5, 6, 7, 8, and 9 here. The last thing that happened was we had a Universe filled with neutral atoms -- mostly hydrogen with some helium and a negligible amount of everything else -- that had begun to collapse under its own gravity.
When a few regions of space got dense enough, about 50 million years into the story, we made the first stars!
But there's a problem when…
elerner | April 27, 2010Stephen Hawking may have been the only person to play himself on Star Trek, but that doesn't mean he's ready to sign Earth up for the United Federation of Planets. The world's most famous living scientist recently reiterated his warning that the search for intelligent life on other worlds could lead to a scenario not unlike the one found in a less optimistic sci-fi staple: Independence Day. The fear--resource-hungry ETs will find us easy pickings--is far from an alien concept; Hawking says his rationale is rooted in human history. Needless to say, there's been some disagreement about Hawking'…
esiegel | April 26, 2010
To confine our attention to terrestrial matters would be to limit the human spirit. -Stephen Hawking
Stephen Hawking is in the news today, big time. Why? He says that intelligent aliens almost certainly exist, and that we should definitely not try to contact them. In fact, he argues, we should stay as quiet as possible and try to avoid detection. To quote him:
If aliens visit us, the outcome would be much as when Columbus landed in America, which didn't turn out well for the Native Americans.
We only have to look at ourselves to see how intelligent life might develop into something we…
elerner | April 26, 2010After a week of excitement—complex volcanism, the 40th Earth Day, and cinematic cephalopods—the weekend brought us the 20th anniversary of the Hubble Space Telescope's launch. On April 24, 1990, Space Shuttle Discovery lugged the silvery tube of mirrors, circuitry, and solar panels into low earth orbit; now both the shuttle and telescope are in the twilight of their careers. Discovery is scheduled to fly the last Space Shuttle mission in September, and while Hubble will likely keep working for a few more years on the back of its final repairs, this anniversary marks the official end of its…
esiegel | April 23, 2010Where there is an observatory and a telescope, we expect that any eyes will see new worlds at once. -Henry D. Thoreau
20 years ago tomorrow, the Hubble Space Telescope was launched into orbit.
It doesn't look that impressive, and maybe it shouldn't. After all, what is a space telescope? It's a couple of mirrors, a camera, some stabilizing gyroscopes, some electronics and an antenna, all wrapped in a reflective coating and powered by some solar panels. Doesn't sound so hard, does it?
But Hubble has vastly increased our understanding of the Universe, and I'd like to share with you some of the…
esiegel | April 22, 2010Note: This article first appeared here on Scienceblogs one year ago today.
There are many ways to celebrate Earth Day, from sustainability efforts to simply appreciating nature.
And while this is a beautiful shot of Forest Park right here in Portland, it doesn't compare -- in my eyes -- to the perfection of Earth as seen from so far away.
In October of 1946, a V-2 missile was launched from New Mexico, straight up into the air. And at its maximum height of 65 miles (just barely into what was then considered outer space), it snapped the first photographs of the Earth from Space. (And you can…