Stars
esiegel | February 11, 2011"It seems like once people grow up, they have no idea what's cool." -Bill Watterson
Well, at least we can all agree on what's not cool. The Sun.
Image credit: NASA, from what looks like the Stereo spacecraft.
With a surface temperature of around 6,000 Kelvins, the Sun is one of the hottest objects that we're all familiar with.
But when it comes to stars, the Sun is merely a "G-type" star. It turns out that there are many types of stars that are -- typically -- more massive, bluer, and hotter than our Sun.
In fact, O-stars, the hottest type, can have surface temperatures over 40,000 Kelvin…
esiegel | February 4, 2011"How'd the moon get here? Look, you pinheads who attacked me for this, you guys are just desperate. How'd the moon get here? How'd the sun get there? How'd it get there? Can you explain that to me? How come we have that and Mars doesn't have it?" -Bill O'Reilly
Once upon a time, humans looked at the tides -- going out and coming in -- and we had no idea what caused them. At high tides, the sea level would rise, and the coast would get swept up by the oceans, while at low tides, the water would recede, leaving tidepools behind.
Image credit: smugmug.com.
Low tides and high tides would each…
esiegel | January 18, 2011"There, peeping among the cloud-wrack above a dark tor high up in the mountains, Sam saw a white star twinkle for a while. The beauty of it smote his heart, as he looked up out of the forsaken land, and hope returned to him. For like a shaft, clear and cold, the thought pierced him that in the end the Shadow was only a small and passing thing: there was light and high beauty for ever beyond its reach." -J.R.R. Tolkien
But over at XKCD, that quote provides little comfort. After all, "for ever" isn't exactly quite right.
Even the stars must all exhaust their fuel and die.
Right?
Let's head on…
esiegel | December 20, 2010"We find them smaller and fainter, in constantly increasing numbers, and we know that we are reaching into space, farther and farther, until, with the faintest nebulae that can be detected with the greatest telescopes, we arrive at the frontier of the known Universe." -Edwin Hubble
There's really only one way to appreciate just how far we've come in our quest to learn about the Universe thanks to the Hubble Space Telescope.
That is, to take a look at something before the Hubble Space Telescope came along, and then to look at it with Hubble. Preferably, we can look at it multiple times, as…
esiegel | December 3, 2010"The image is more than an idea. It is a vortex or cluster of fused ideas and is endowed with energy." -Ezra Pound
Back in the 1800s, observational astronomy was already entering its heyday. We had already discovered Uranus, the first planet not visible to the naked eye, knew of a number of comets and asteroids, and had a whole catalog of "bizarre" objects in the sky.
Some turned out to be star clusters, globular clusters, remnants of exploded stars, or other galaxies entirely! But one of the unfortunate things about astronomy around 1800 is that the Southern Hemisphere objects were grossly…
esiegel | October 14, 2010Calvin: Why does the sky turn red as the sun sets?
Calvin's Dad: That's all the oxygen in the atmosphere catching fire.
Calvin: Where does the sun go when it sets?
Calvin's Dad: The sun sets in the west. In Arizona actually, near Flagstaff. That's why the rocks there are so red.
Calvin: Don't the people get burned up?
Calvin's Dad: No, the sun goes out as it sets. That's why it's dark at night.
Calvin: Doesn't the sun crush the whole state as it lands?
Calvin's Dad: Ha ha, of course not. Hold a quarter up. See, the sun's just about the same size.
Calvin: I thought I read that the sun was…
esiegel | September 27, 2010"I know all about neutrinos, and my friend here knows about everything else in astrophysics." -John Bahcall
Neutrinos are the most poorly understood particles in the standard model. Remember the standard model?
The standard model of elementary particles tells us what the fundamental constituents of matter and forces are in our Universe. We have the force carriers -- photons, gluons, W's and Z's, and the Higgs -- that are responsible for every force in the Universe except gravity. We've got the six quarks (up, down, strange, charm, bottom, and top), that are responsible for the proton, the…
esiegel | August 17, 2010Be careful whose advice you buy, but, be patient with those who supply it. Advice is a form of nostalgia, dispensing it is a way of fishing the past from the disposal, wiping it off, painting over the ugly parts and recycling it for more than it's worth.
But trust me on the sunscreen. -Baz Luhrmann
Our Sun gives us practically all of the light and energy our planet receives, and it does it, at its core, by fusing light elements into heavier ones.
And even though this nuclear fushttp://en.wikipedia.org/wiki/Gamma_rayion releases a tremendous amount of very high energy photons (known as gamma…
esiegel | July 22, 2010"The light that burns twice as bright burns for half as long - and you have burned so very, very brightly, Roy. Look at you: you're the Prodigal Son; you're quite a prize!" -Tyrell, from Blade Runner
Look up at the night sky. On a clear, dark night with normal vision, you can literally see thousands of stars.
Some of them are barely visible, others shine so brightly that they come out when the sky's still blue! Why do some appear brighter than others? Two reasons. Some stars are simply closer to us, but others, intrinsically, shine spectacularly bright. Let's take a look at a small section…
esiegel | July 12, 2010Yo ho! It's hot, the sun is not a place where we could live.
But here on earth there'd be no life without the light it gives.
We need its light. We need its heat. We need its energy.
Without the sun without a doubt there'd be no you and me. -They Might Be Giants
Ahh, the Sun. Beautiful and blinding to the naked eye, it's still the source of energy that gave rise to all of the life on Earth that we know.
Image credit: GOES satellite, in the X-ray.
The Sun emits energy all over the light spectrum, from long-wavelength radio waves (many meters long) to visible light to X-rays (just a small…
esiegel | July 10, 2010"We want our sound to go into the soul of the audience, and see if it can awaken some little thing in their minds... 'Cause there are so many sleeping people."
-Jimi Hendrix
One of the greatest challenges in music is to take a great original song and cover it, adding your own twist or flavor, and produce something that's even better. Most of you have heard the Four Tops' song It's the Same Old Song, which has its own interesting story.
It's The Same Old SongBut this past week, I discovered a cover of it by Iron & Wine, which kind of, well, awakened something inside of me listening to it.…
esiegel | July 9, 2010"I admitted, that the world had existed millions of years. I am astonished at the ignorance of the masses on these subjects. Hugh Miller has it right when he says that 'the battle of evidences must now be fought on the field of the natural sciences.'"
-James A. Garfield, future U.S. President, in 1859
You will find all sorts of ideas out there on how old the Earth, the Galaxy, and the Universe are. Some contend that it's only a few thousand years old, while others contend that it's infinitely old.
You and I are free to believe whatever we want, of course. But before you decide what you…
esiegel | June 18, 2010"No pessimist ever discovered the secret of the stars, or sailed to an uncharted land, or opened a new doorway for the human spirit." -Helen Keller
If you've been paying attention, you heard that the Kepler mission, earlier this week, announced the discovery of 706 candidate planets orbiting stars in its field of view.
And while most of the planets it found were Neptune-sized or smaller, they were still mostly gas giants, and still mostly closer than Mercury to their parent stars. Kepler's looking at 100,000 stars, and while finding 706 planets is certainly not bad for just over a month's…
esiegel | June 17, 2010"We are all captives of the pictures in our head -- our belief that the world we have experienced is the world that really exists." -Walter Lippmann
For a long time, humans have wondered about life on other worlds, and about worlds around other stars. Until the 1990s, this was mostly speculation and hope. But shortly thereafter, some clues started rolling in. In 1992, the first planet outside of our Solar System was detected, and three years later, the first planet around a solar-like star was found.
Only, something was awfully weird about this planet. You see, in our Solar System, Mercury…
esiegel | June 10, 2010"A good heart is the Sun and the Moon; or, rather, the Sun and not the Moon, for it shines bright and never changes." -William Shakespeare
Did I ever tell you how lucky you are?
Lucky, indeed, to have the Sun for a star?
Our Sun -- the ultimate source of all the light, heat, energy, and life on our world -- is remarkable in how constant it is. In fact, we didn't even know just how constant it was until we launched the SOHO satellite, shown below.
SOHO has just released their results from more than 12 years of observing the Sun from space, and found that the size of the Sun has been constant…
drorzel | June 10, 2010One of the questions asked of Neil deGrasse Tyson at the WSF thing last week was "When did you change from a mild-mannered astrophysicist to a rock-star scientist?" (or something close to that phrasing). In his answer, he said that after his first tv interview was edited down to a three-second shot of him wiggling his hips, he made a deliberate effort to practice giving sound bites-- answering questions in 3-4 sentences with a good "hook" for the tv people to work with.
I thought of this when I stumbled across the following YouTube clips, which were shot by TV Ontario when I was at the…
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…
esiegel | May 19, 2010"I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet. The function of man is to live, not to exist. I shall not waste my days trying to prolong them. I shall use my time." -Jack London
Most of you have seen a shooting star before, also known as a meteor.
They happen most frequently during (surprise) meteor showers, but occasionally (and sparsely) during other times of the year. Whenever a small bit of astronomical dust from outer space runs into the atmosphere -- even though it may be no bigger than a grain of sand -- it burns up in the…
cevans | May 19, 2010
What are stars?
Despite their ubiquity in our universe, their praises often go unsung. A friend admitted to me once that he hadn't realized -- you know, really viscerally realized -- that our sun was itself a star until he was in his twenties. From that moment forward, however, every glance at the night sky bowled him over with such an emotion of vast familiarity that he could hardly stand to look at it. And with just cause: every star, like our sun, is a wonder, a factory producing almost all the heavy elements floating around the cosmos -- including the everyday matter that makes up 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,…