Solar System
esiegel | September 28, 2011"If you ever drop your keys into a river of molten lava, let 'em go, because, man, they're gone." -Jack Handey
Take a look at our home planet, Earth, and one of the things you'll notice is that over 70% of the surface is coated in water.
Image credit: NASA / Apollo 17.
We all know why this is, of course: it's because the Earth's oceans float atop the rocks and dirt that make up what we know as land.
This concept of floatation and buoyancy -- where the less dense objects rise above the denser ones, which sink to the bottom -- does much more than just explain the oceans.
This same principle…
esiegel | September 6, 2011"We have found a strange footprint on the shores of the unknown." -Arthur Eddington
Since the dawn of mankind, we've left innumerable footsteps across the lands, as we've traveled far and wide across the globe.
Image credit: Greg Prohl.
But (with very rare exceptions) these footsteps don't last. With winds and/or rains abundant all over Earth, among many other phenomena, it's usually just a brief matter of time until all memory of these footsteps are removed from the shifting landscape.
Image credit: Byron Jorjorian.
But what about a world without winds and rains? What about, in fact, a…
esiegel | August 30, 2011"My girl, my girl, don't you lie to me,
tell me where did you sleep last night?
In the pines, in the pines, where the Sun don't ever shine,
I'll shiver the whole night through." -Leadbelly, among many other variations
It's already been a couple of months since I wrote about Global Warming, and was deluged with comments that (to be kind) objected to the scientific consensus that the Earth is getting warmer, and humans are very likely the cause.
So let's just take a look at the basic physics of how a warm object -- like a planet -- stays as warm as it does in a cold environment, like…
esiegel | August 20, 2011"An appeaser is one who feeds a crocodile, hoping it will eat him last."
-Winston Churchill
Ever wonder what will happen to the Earth once the Sun dies? Although it's happening very slowly, the Sun is burning through the nuclear fuel that powers it, giving off a tremendous amount of energy all the time as it happens.
Image credit: NASA's STEREO A spacecraft.
Like all stars, the Sun burns progressively hotter as it ages. A few billion years ago, solar output was 10% less than it is today, and a few billion years from now, it will burn so hot that our oceans will boil, something that only…
esiegel | August 10, 2011"Failure is simply the opportunity to begin again, this time more intelligently."
-Henry Ford
Back in 2003, a twin pair of rovers -- Spirit and Opportunity -- were launched from Earth to Mars. For no good reason at all, Opportunity has long been my favorite of the two.
Image Credit: NASA / JPL, as are all the Opportunity rover pictures.
Opportunity landed in January of 2004 in Eagle Crater, a relatively small crater on the surface of Mars. Originally slated for a 90-day mission, Opportunity has been going strong for nearly seven years now!
Over that time, it's made some amazing discoveries…
esiegel | August 9, 2011"Magnetism, as you recall from physics class, is a powerful force that causes certain items to be attracted to refrigerators." -Dave Barry
One of the first "invisible forces" people encounter in this world is when they're first exposed to the humble magnet.
As the image above shows, you're most familiar with what magnets do to other magnetic (or magnetizable) materials, like the paper clip.
But magnets also exert forces on electrically charged objects. They do it, though, in a way that you're certainly not used to. Unlike gravity, where the gravitational field pulls you in the direction of…
esiegel | August 4, 2011"You develop an instant global consciousness, a people orientation, an intense dissatisfaction with the state of the world, and a compulsion to do something about it. From out there on the Moon, international politics looks so petty. You want to grab a politician by the scruff of the neck and drag him a quarter of a million miles out and say, 'Look at that, you son of a bitch.'" -Edgar Mitchell, Apollo 14 Astronaut
It was nearly 50 years ago that we left Earth for the first time.
Image credit: B. Anders, Apollo 8, NASA, in 1968.
We've walked on the Moon.
Image credit: Voyager 1, NASA, in…
esiegel | July 13, 2011"Either you repeat the same conventional doctrines everybody is saying, or else you say something true, and it will sound like it's from Neptune." -Noam Chomsky
Except back before it was discovered, the very idea of Neptune... well... sounded like it was from Neptune!
Image credit: Voyager 2, NASA.
The planets out to Saturn are visible with the naked eye, and have been known since at least the time of the ancient Greeks. While the telescope was first invented in the early 1600s, it wasn't until 1781, nearly 200 years later, that the next planet -- Uranus (above) -- was discovered.
But…
esiegel | June 27, 2011"Doubt, indulged and cherished, is in danger of becoming denial; but if honest, and bent on thorough investigation, it may soon lead to full establishment of the truth." -Ambrose Bierce
About a week and a half ago, I wrote an article called The Power of Theory In Science, where I mentioned the Big Bang, Evolution, and Global Warming as some of the leading scientific theories describing a variety of natural phenomena.
Image credit: Rhys Taylor, Cardiff University.
And while no one took issue with my assertion that the Big Bang and Evolution were the best scientific theories describing (…
esiegel | June 14, 2011"It is one of life's bitterest truths that bedtime so often arrives just when things are really getting interesting." -Lemony Snicket
Those of you who live basically anywhere other than North America are in for a treat this Wednesday. All over Earth, of course, the Moon is nearing its "full" phase, where the half of the Moon illuminated by the Sun is completely visible from Earth.
And it will reach complete fullness on Wednesday night.
Now, most times, when this happens, the full Moon is completely visible from everywhere on Earth. But every so often -- about twice a year on average -- the…
esiegel | May 7, 2011"If you're going to do something tonight that you'll be sorry for tomorrow morning, sleep late." -Henny Youngman
Normally, the best wonders of the night sky -- stars, planets and beyond -- happen, well, late at night. But every once in a while, it's actually the very early morning sky that holds the greatest sights. Just make sure you get up before -- as David Grisman and Tony Rice might tell you -- your sky is ruined by the
Morning Sun.Why's that? Well, if you look to the East, just before sunrise, you might see a sight like this:
Image credit: Luis Argerich.
Well, what do we have here?…
esiegel | April 22, 2011"We came all this way to explore the moon, and the most important thing is that we discovered the Earth." -Bill Anders, Apollo 8 Astronaut
This Earth Day, I think -- for anyone interested in space, astronomy, or the Universe -- gives us perhaps the best opportunity to look back on our planet as we understand it now, having traveled so far away from it.
It was only, believe it or not, back in the 1940s that we first photographed our planet from high enough up to directly observe that, in fact, the Earth is curved!
The above image, from 1948 in space over New Mexico, was the first panorama…
esiegel | April 11, 2011"Life's but a walking shadow, a poor player, that struts and frets his hour upon the stage and then is heard no more; it is a tale told by an idiot, full of sound and fury, signifying nothing." -William Shakespeare
Ahh, the glorious shadows of our Universe. Everywhere that sunlight is blocked gives us shadow.
Image credit: Kaguya (Selene).
For the Earth, of course, this results in night and day each time the Earth rotates.
The Earth, though, is also tilted on its axis a significant amount, by about 23.5 degrees. When a pole tilts towards the Sun, it receives continuous daylight, while when…
esiegel | March 23, 2011"I came from the country, and when I came to the city, I was ridin' high, you know. I was seeing more lights than I ever dreamed to shine in the world. 'Cos where I came from, there wasn't too many lights. Bugs made a lot of light, but after that there wasn't no lights." -John Hunter
John Hunter should have been at a higher latitude! Because if you're fortunate, at a high enough latitude (either north or south), the following sight will sometimes greet you in the night sky.
Image credit: Thundafunda.com.
In the northern hemisphere, we call it the Aurora Borealis, while the southern gets the…
esiegel | March 17, 2011"Don't tell me the moon is shining; show me the glint of light on broken glass." -Anton Chekhov
Ahh, Chekhov, you old sour puss, what do you have against the brilliance of our Moon?
Beautiful in our sky, the Moon typically takes up half-a-degree in the night sky, where it's by far the largest and brightest object visible to the naked eye (well, for those of you who can't see the full Andromeda galaxy with your naked eye). But the Moon actually varies in its apparent size in the sky! If you photograph the Moon when it appears to be at its largest, it actually appears about 14% bigger than…
esiegel | March 10, 2011"All truths are easy to understand once they are discovered; the point is to discover them." -Galileo Galilei
Ever since the time of Galileo, Jupiter has been an amazing sight for skywatchers. With its four large moons, even the smallest of amateur telescopes provide amazing sights.
In fact, if you watch Jupiter's four large Moons over the span of a few hours, you're likely to discover the same exact thing that Galileo did.
You can see that Jupiter's moons orbit around Jupiter! Looking through a larger telescope, like the video above was shot using, you can actually see the shadows of…
esiegel | March 3, 2011"Old men and comets have been reverenced for the same reason: their long beards, and pretenses to foretell events." -Jonathan Swift
Last week, I showed you the new, highest-resolution mosaic ever made of the near side of the Moon.
And I also showed you a small, somewhat unusual feature that I named "Snakey."
Snakey isn't all that impressive, of course. What might strike you as unusual, however, is that it appears to be a chain of craters, found close together, making a (roughly) straight line!
But there is a far better example. Much thanks goes to our reader, Tom Scrace, who was looking at…
esiegel | February 25, 2011"Everything has a natural explanation. The moon is not a god, but a great rock." -Anaxagoras
The Moon, as you well know, is one of the spectacular sights of the night sky, especially when it's full.
Image credit: Luc Viatour.
Even those of us with imperfect vision can see differences between the large, dark areas (known as maria) of dried-up lava beds and the bright, white mountainous regions. But through even the smallest of telescopes or binoculars, brilliant features -- invisible to the naked eye -- emerge.
Image credit: Naoyuki Kurita.
One of the largest craters on the Moon,…
esiegel | February 23, 2011"Leading scientists are warning that a massive solar storm could trigger a $2 trillion 'global Katrina' that short-circuits power grids worldwide." -Lesley Taylor
If you've been keeping up with your online news lately, you may have heard that, undoubtedly, an impending Solar Storm will cause hundreds of billions -- if not trillions -- of dollars of damage.
The impending storm has been compared to a global Hurricane Katrina. What's the hullaballoo about?
Last week, the Sun launched forth a powerful Solar Flare, as imaged above by NASA's Solar Dynamics Observatory. What was the big effect of…
esiegel | February 15, 2011"I have announced this star as a comet, but since it is not accompanied by any nebulosity and, further, since its movement is so slow and rather uniform, it has occurred to me several times that it might be something better than a comet. But I have been careful not to advance this supposition to the public." -Giuseppe Piazzi
When we think of the planets, most of you think of either eight or nine, depending on whether you count Pluto or not.
But you all know Pluto's story. Eighty-one years ago, a lone astronomer looking at the same few patches of sky, night-after-night, would look for any…