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The first Death Star from Star Wars (via Wookieepedia)

Obi-Wan: That’s no moon. It’s a space station.

That space station was the Empire’s first Death Star in Star Wars: A New Hope. Obi-Wan and company had just bounced through a debris field, the remnants of the planet Alderaan. Such an act of destruction would seem impossible to us–it seemed so to many of the movie’s characters until it happened. But perhaps not, say three students at the University of Leicester in England who last year published a study on the subject in their university’s undergraduate physics and astronomy journal.

The study’s authors start off by making some simple assumptions: The planet being fired upon doesn’t have some sort of protection, like a shield generator. And it’s about the size of Earth but solid through and through (Earth isn’t solid, but the planet’s layers would have significantly complicated the math here). They then calculate the planet’s gravitational binding energy, which is the amount of energy required to pull apart an object. Using the mass and radius of the planet, they calculate that destruction of the object would require 2.25 x 10³² joules. (One joule is equal to the amount of energy required to lift an apple one meter. 10³² joules is a lot of apples.)

The energy output of the Death Star isn’t given directly in the movie, but the space station was said to have had a “hypermatter” reactor that had the energy output of several main-sequence stars. For an example of a main-sequence star, the authors look to the Sun, which puts out 3 x 10²⁶ joules per second, and they conclude that the Death Star could “easily afford to output [the energy required for an Earth-like planet's destruction] due to to its tremendous power source.”

It would be a different story, though, if the planet scheduled for destruction had been more like Jupiter than Earth. The gravitational binding energy of Jupiter is 1,000 times that of the Earth-like planet in the study. “To destroy a planet like Jupiter [the space station] would probably have to divert all remaining power from all essential systems and life support, which is not necessarily possible.”

Of course, that assumes that the Emperor wouldn’t be willing to sacrifice a space station full of people to wipe out his enemies. And considering that he was just fine with wiping out whole planets, I’m not sure I’d take that bet.

A composite image of S106, from the Hubble Space Telescope and Japan's Subaru Telescope (Credits: NASA/ESA/the Hubble Heritage Team (STScI/AURA)/NAOJ)

About 2,000 light years away, in the direction of the constellation Cygnus (The Swan), in a rather isolated part of the Milky Way, lies a newly formed star known IRS 4. This star, about 15 times the mass of our Sun, is still so young that it hasn’t yet calmed down; it’s ejecting material at high speed, giving this image its wings. That hydrogen gas, colored blue here, is heated by the star to temperatures of 10,000 degrees Celsius, making them glow. The cloudy, red parts in the image are tiny particles of dust illuminated by the star.

This area of the universe is known as star-forming region S106 and it’s pretty small (well, by universe standards), at only two light years from the edge of one “wing” to the other. The nebula is also home to more than 600 known brown dwarfs, “failed” stars that, because of their size, less than a tenth the mass of our Sun, cannot undergo the nuclear fusion that powers glowing stars.

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The best place to find "aliens" might be Comic-Con (2008, credit; Jim Merithew/Wired.com, via Wired Photostream on flickr)

A 2010 poll found that one in four Americans (and one in five people worldwide) believe that aliens have visited our planet. And many of these people believe that the evidence of these visits has been covered up by the government. Area 51, Roswell, mutilated cows in Colorado—there’s got to be some truth in that, right? And so two petitions were created on the White House We The People site, one calling “for the President to disclose to the American people the long withheld knowledge of government interactions with extraterrestrial beings” and the other asking the President “to formally acknowledge an extraterrestrial presence engaging the human race.”

The petitions easily reached the threshold of 5,000 signatures needed to get a response from the White House. But the signers are likely to be disappointed. Phil Larson, who works on space policy and communications at the White House Office of Science & Technology Policy, wrote in the response:

The U.S. government has no evidence that any life exists outside our planet, or that an extraterrestrial presence has contacted or engaged any member of the human race. In addition, there is no credible information to suggest that any evidence is being hidden from the public’s eye.

He gives a few examples of ongoing and planned research—SETI, Kepler, the Mars Science Laboratory—that may lead to the discovery of alien life and then reminds us that the odds of finding alien life are probably pretty slim:

Many scientists and mathematicians have looked with a statistical mindset at the question of whether life likely exists beyond Earth and have come to the conclusion that the odds are pretty high that somewhere among the trillions and trillions of stars in the universe there is a planet other than ours that is home to life.

Many have also noted, however, that the odds of us making contact with any of them—especially any intelligent ones—are extremely small, given the distances involved.

While reading this, I was reminded of a conversation I had with Cassie Conley last year when I was reported a story about what will happen should we actually find alien life. Conley is NASA’s Planetary Protection Officer; she’s the one who makes certain that NASA missions don’t contaminate other planets and that any sample return missions don’t harm us here on Earth. She told me that after she took the NASA job, some people befriended her in the hopes of ferreting out NASA’s secrets about aliens. “I was dropped as an acquaintance immediately upon their realizing that, in fact, I didn’t have any secrets,” she said. “They were disappointed when they found out there weren’t any.” (But at least she had a good attitude about it all: “It was rather entertaining,” she said.)

I will admit that it is possible that some grand conspiracy exists, that a government or corporation could be hiding this information from us all. (I can’t disprove a negative.) But keep in mind what Conley says: “If you think the U.S. government is that good at keeping secrets, you’ve got a lot higher opinion of them than I do.”

In addition, such a conspiracy would necessitate excluding the scientists most interested and most qualified in this area, and all of them have committed to making a discovery of alien life public. “I think there’s a big misconception in the public that somehow this is all a cloak-and-dagger operation,” says Arizona State University astrobiologist Paul Davies. “It’s not. People are quite open about what they are doing.”

Even the White House.

Anyone dressing up as a mad scientist today? (courtesy of flickr user contains_caffeine)

It’s Halloween and if you don’t have a costume yet, obviously you’ve got little time to put one together. But that’s OK, because we’ve dug up a few ideas for easy costumes with a science theme:

1 ) Mad Scientist: Yes, it’s an obvious one, but it will be easy to put together. All you need is messy hair, a geeky t-shirt (if you don’t have one, just take a plain shirt and write a few equations on it) and/or white lab coat, perhaps some safety goggles or protective gloves, and a glass container (a beaker or Erlenmeyer flask would be nice) with some colored liquid, bubbling away with the addition of some dry ice.

2 ) The Pacific Garbage Patch: This idea, from the Mother Nature Network, requires only some blue clothing and whatever bits of plastic you’ve got lying around the house. Glue or otherwise attach the plastic bits in a large patch to your outfit, get a little background info on the problem so you can inform anyone who asks, and you’ll be good to go.

3 ) Schrödinger’s Cat: This is a classic example of a feature of quantum physics in which something can be in two states simultaneously. Schrödinger’s Cat is in a box and is both dead and alive. For this costume, you’ll need a box to wear (at least over your head, like idea number 1 here) with a flap cut out for your face. Give yourself whiskers and a cute cat nose.

4 ) Squid: There are plenty of reasons to love these undersea creatures. But the ability to make a squid hat using nothing more than paper and a couple of CDs (as seen here on Discoblog) is another.

5 ) Dark Energy or Dark Matter: Find a “My Name Is” sticker and write “Dark Energy” or “Dark Matter” on it. No one knows what either of them looks like, so your guess (whatever you’re wearing) is as good as any other.

(And if you haven’t yet carved your pumpkin, be sure to check out these ideas from around the Smithsonian.)

An artist's conception of the star LkCa 15 and the nearby protoplanet. (Credit: Karen L. Teramura, UH IfA)

Planets form from disks of swirling material that condense into solid bodies. Once only a theory, this formation has now been caught in the act by scientists using telescopes at the W.M. Keck Observatory in Hawaii (a site that should be familiar if you’ve read the Smithsonian story on black holes). The planet’s name is LkCa 15 b and researchers say it’s a protoplanet (below, in blue), still surrounded by cool dust and gas (in red). “We…found a planet, perhaps even a future solar system at its very beginning,” says the University of Hawaii’s Adam Kraus, lead author of the study that will appear soon in the Astrophysical Journal.

The planet LkCa 15 b appears in blue surrounded by cooler dust and gas in red, near the star LkCa 15. (Credit: Kraus & Ireland, 2011)

Kraus and his co-author, Michael Ireland of Australia’s Macquarie University, made their discovery by combining two techniques to cancel out the light from bright stars. The first is adaptive optics, which uses powerful computers to rapidly manipulate the telescope’s mirrors and adjust for distortions caused by Earth’s atmosphere. The second is aperture mask interferometry, and it further improves the resolution of the telescope. “We can manipulate the light and cancel out distortions,” Kraus says. They pointed the telescope at the star LkCa 15, canceled out the star’s light and there it was, a newly forming planet.

“LkCa 15 b is the youngest planet ever found,” Kraus says. “This young gas giant is being built out of the dust and gas….For the first time, we’ve been able to directly measure the planet itself as well as the dusty matter around it.”

Phil Plait, at Bad Astronomy, has more details:

The disk’s hole is about 8 billion km across. Disks like this are seen around other stars, and it’s generally thought that the hole is caused by a planet orbiting inside that region sweeping up material. In this case, that looks to be true! If the planet is in a circular orbit, it’s about 2.5 billion kilometers from its star, a little closer to its star than Uranus is from the Sun (it’s not known if the orbit is circular or elliptical; that’ll take a few years of observations as the planet physically moves around the star and the orbit can be calculated). The planet is much hotter than you might expect, but that’s because it’s so young: material is falling onto it, heating it up. That’s why it’s glowing in the infrared.

…Nothing like this has been seen before in a planet so young! That’s scientifically quite important. Our models of how planets form are complex, and we need detailed observations to see if the models are correct or not. Since planet formation is a process, we need observations of it at different stages, including very early on. That’s crucial, since it represents the transition period between the time before planets start to form in the disk, and the time when the planets are all finished and tidied up. We’ve seen both of those before, so this observation is a first.

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