sagansense:

Vaporizing Planets In The Name Of Science

One sure-fire way to grab an audience’s attention is to vaporize a planet, amirite? We saw the destruction of Vulcan in Star Trek, the end of Krypton in the Christopher Reeves-era Superman, while the Death Star vaporized Alderaan in Star Wars: A New Hope.

As for Hitchhikers Guide to the Galaxy, Douglas Adams went all in, vaporizing the Earth right off the bat, all because an alien race known as the Vogons want to make way for a hyperspatial express route, leaving poor Arthur to roam about the Milky Way in his bathrobe.

But can you really vaporize a planet? According to the latest computer simulations by a couple of planetary scientists in St. Louis, you betcha! As outlined in their new paper in The Astrophysical Journal, Bruce Fegley and his colleagues (Katharina Lodders and Laura Schaefer) mathematically constructed a couple of model “Super-Earths” and put them through a series of atmospheric simulations.

The object wasn’t really to study how to destroy the Earth. Fegley et al were trying to learn more about the kinds of atmospheres most likely to be found on Super-Earths — i.e., exoplanets with masses that are more than that of Earth but less than that of Neptune, while still being rocky in nature, instead of, say, a gas giant.

Having detailed knowledge of likely chemical compositions could help astronomers who hunt for such planets find them. And one way of gaining that knowledge is to build computer models of Super-Earths and vaporize them.

Most exoplanets within that size range that have been found are gaseous in nature, because they orbit so close to their host stars that any rocky stuff gets melted. (How Stuff Works has an excellent summary of the various techniques astronomers use to hunt for exoplanets.)

For instance, using photometry, astronomers can detect an exoplanet as it transits the host star, because of predictable periodic dimming of a star’s brightness as the planet momentarily blocks its light. Astronomers can also determine the chemical composition of said planet’s atmosphere because the star’s light gets filtered through that atmosphere — think of it as stellar spectroscopy.

This, in turn, provides clues as to the planet’s density, because the gases in the atmosphere likely came about because of vaporized rock. So it would be nice to have tidy simulated models to compare with the measured spectra of actual exoplanets.

One model Super-Earth had a continental crust just like our Earth, dominated by granite, while the other simulated Earth’s composition before its crust formed, when it was mostly bulk silicate. (Water is the key ingredient in getting Earth today from that precursor Earth. Without it, our planet’s crust would more closely resemble Venus.)

Then they plugged in the likely surface temperatures of observed Super-Earths, ranging from between 270 to 1700 degrees Celsius, just to see what would happen to the atmosphere. “The vapor pressure of the liquid rock increases as you heat it, just as the vapor pressure of water increases as you bring a pot to boil,” Fegley explained via press release. “Ultimately this puts all the constituents of rick into the atmosphere.”

In both models, the atmospheres would likely be mostly steam and carbon dioxide. Once the Super-Earths achieved temperatures above 760 degrees Celsius, there would also be sulfur dioxide. Think an especially steamy Venus.

And at temperatures higher than 1430 degrees Celsius, the uber-heated rock would produce silicon monoxide vapor. Even exoplanetary atmospheres have “weather,” so should a “storm front” move through at those extreme temperatures, the simulations showed that the silicon monoxide could condense and produce “pebble rain.”

Crank the temperature really, really, high, and you wouldn’t just vaporize the Earth’s crust and mantle. Theoretically, at least, you could destroy the entire planet. “You’re left with a big ball of steaming gas that’s knocking you on the head with pebbles and droplets of liquid iron,” said Fegley. “But we didn’t put that into the paper because the exoplanets the astronomers are finding are only partially vaporized.”

Or maybe they just didn’t want to give the Vogons any bright ideas.

Image credit: Fsgregs, at the English language Wikipedia project, Creative Commons.

Article credit: discovery.com

crookedindifference:

Kickstarter: Fight For Space - Space Program & NASA Documentary

“Fight for Space” is a feature length documentary film that explores the current state and future of the U.S. space program. Since the Apollo era of the 1960s, NASA’s budget has been shrinking and our ambitions in space have been decreasing. We are producing a documentary that will examine the reasons why our space program is not all it can be. We are also going to show that space IS worth the time, money, and energy that it needs, not for only exploration and scientific reasons but for economic, planetary security, and cultural reasons as well. We will also be covering the great scientific achievements that NASA is making right now, and we will be examining the new commercial space enterprise by companies like SpaceX, Sierra Nevada, Bigelow, and more. Many problems have occurred in just the past 10 years that have lead to the consistent underfunding of NASA, the cancellation of multiple space systems, and the decline of America’s role in space.

We are not producing your average space documentary where we show restored footage from the moon landings and CGI galaxy renderings. We are covering the real political and economic issues of the recent past, today, and tomorrow. We are covering both sides of the argument and we promise to produce a fair and objective film.

The fact is, the United States as a nation has lost our edge in space, not just as a leader but even as a participant. We want to know the real reasons behind why we are in this scientific slump and what we can do about it. We are asking hard questions to the people that know what is going on and we will not stop until we receive real answers and real solutions to these problems. We are also speaking with everyday citizens off the street, so we can discover how the American public feels about space exploration. In our democracy, all voices must be heard.

theabominationisinsane:

jtotheizzoe:

Time Stands Still

Tonight’s “leap second” and why the Earth sucks at keeping time

If you stand very still tonight, holding your breath in the still of midnight darkness, you’ll hear the sound of all the clocks in the world pausing for one second. Actually, you probably won’t hear anything, but you should know that today will be one second longer than a normal day. Why?

When trains began to make long-distance travel possible, with schedules dependable down to the minute, there was a worldwide demand for standardized time. So we got Greenwich Mean Time, which defined the measure of a day as the average time of a single rotation of the Earth from the perspective of one Englishman staring up at the sky in Greenwich. In 1820, this just so happened to be 86,400 seconds, or 24 hours.

The problem is that the Earth’s rotation is slowing down, and a “solar day” isn’t exactly 86,400 seconds anymore. The Earth doesn’t care about our time system one bit, apparently.

How does that work? The Moon pulls on the Earth due to its own gravity. When that’s combined with the natural gravity of the Earth, we get two “high-tide” bulges on opposite sides of our planet. But the bulges don’t line up perfectly with the equator, and the Moon actually pulls on the ocean enough to create a tiny amount of friction. That friction is slowing our rotation by about 0.002 seconds per day per century. Eventually the Earth and Moon will be “tidally locked” and each will have a constant face to the other (like the Moon does to Earth today). Phil Plait explains this all pretty well here. Moreover, earthquakes and all sorts of other stuff mean that this “slowing” business is also irregular. 

Earth sucks as a timepiece.

Since the 1970’s, our “official time” has been kept by atomic clocks, accurate to one second every 250 million years. We actually changed the official definition of a second to be based on atoms instead of 1/86,400th of a day. But many traditional clocks, not to mention our bodies, are basing their day on day/night averages, and the atomic clocks are basing it on cesium atoms (far more accurately). The day/night clocks are lagging behind! So on a regular basis, the Time Lords of Earth let the atomic clock time pause for one second to bring them closer to sync. That’s a leap second.

If we didn’t do this, and just let the clocks go their separate ways, we might cause serious problems to systems like GPS software that depend on super-super-accurate time-keeping. 

So tonight, the official clocks will show 23:59:60 before rolling over to tomorrow, and everything is in its right place. Don’t worry if you forget to sync your watch. You’ll just be a second early everywhere tomorrow.

More detailed factoids from Phil Plait at Bad Astronomy.

I’ll be spending my extra second sleeping.

quantumaniac:

Black Hole Lensing

This is a simulation of gravitational lensing caused by a black hole going past an arbitrary galaxy. Gravitational lensing is an effect that occurs when a large cluster of matter occurs between an object and an observer, such as a black hole in between a galaxy and an Earthly observer. As the light travels from the galaxy to the observer, the intense gravity of the black hole bends the light - due to the curvature of spacetime around the object. 

A secondary image of the galaxy can be seen within the black hole Einstein ring on the opposite direction of that of the galaxy. As the primary image approaches the black hole, the secondary image grows (but remains within the Einstein ring). The maximum amplification occurs when the background galaxy (or in the present case a bright part of it) is exactly behind the black hole.

thenewenlightenmentage:

Runaway Planets Zoom at a Fraction of Light Speed

ScienceDaily (Mar. 22, 2012) — Seven years ago, astronomers boggled when they found the first runaway star flying out of our galaxy at a speed of 1.5 million miles per hour. The discovery intrigued theorists, who wondered: If a star can get tossed outward at such an extreme velocity, could the same thing happen to planets?

New research shows that the answer is yes. Not only do runaway planets exist, but some of them zoom through space at a few percent of the speed of light — up to 30 million miles per hour.

Read More

thequantumlife:

Gravity bends more than just space. It bends time.

The early results from Gravity Probe B, one of Nasa’s most complicated satellites, confirmed yesterday ‘to a precision of better than 1 per cent’ the assertion Einstein made 90 years ago - that an object such as the Earth does indeed distort the fabric of space and time.

But this - what is referred to as the ‘geodetic’ effect - is only half of the theory. The other, ‘frame-dragging’, stated that as the world spins it drags the fabric of the universe behind it.

[…]

According to Einstein, in the same way that a large ball placed on a elasticated cloth stretches the fabric and causes it to sag, so planets and stars warp space-time. A marble moving along the sagging cloth will be drawn towards the ball, as the Earth is to the Sun, but not fall into it as long as it keeps moving at speed. Gravity, argued Einstein, was not an attractive force between bodies as had been previously thought.

That probably didn’t clarify it any. But there’s more!

When Einstein wrote his general theory of relativity in 1915, he found a new way to describe gravity. It was not a force, as Sir Isaac Newton had supposed, but a consequence of the distortion of space and time, conceived together in his theory as ‘space-time’. Any object distorts the fabric of space-time and the bigger it is, the greater the effect.

Just as a bowling ball placed on a trampoline stretches the fabric and causes it to sag, so planets and stars warp space-time - a phenomenon known as the ‘geodetic effect’. A marble moving along the trampoline will be drawn inexorably towards the ball.

Thus the planets orbiting the Sun are not being pulled by the Sun; they are following the curved space-time deformation caused by the Sun. The reason the planets never fall into the Sun is because of the speed at which they are travelling.

According to the theory, matter and energy distort space-time, curving it around themselves. ‘Frame dragging’ theoretically occurs when the rotation of a large body ‘twists’ nearby space and time. It is this second part of Einstein’s theory that the Nasa mission has yet to corroborate.

Read more!

 

 

thats-so-meme:

http://joe861.tumblr.com/

Let me correct my poor word choice:

Age is the length of time that a person has lived, yes; 

but an interesting fact is that since each year on each planet is longer or shorter, your age can change from planet to planet. That does not mean that the length of your life has gotten longer or shorter, it just means that the planet’s rotation around the sun is shorter or longer.

Ex: Calculate your age on each planet by dividing your age on Earth by the number of years it takes a given planet to make a full rotation around the sun.

(Source: invaderxan)