Science: Earth Gets Billion-Year Life Extension

From Denny: It seems like every few years scientists decide the Earth is really an older planet and, oh, by the way, they think the sun will exist for a few million or so years longer. Not to worry, folks, we will still have a home for mankind for a little while longer! :) Here's the latest from Wired.com's Wired Science blog.

"The Earth could be habitable for another 2.3 billion years, extending previous estimates of life’s horizon by more than 1 billion years.

King Fai Li and his colleagues at Caltech hypothesize that Earth’s atmospheric pressure has always varied, and that it could fall in the distant future, keeping Earth from frying for far longer than previous research had shown.

If the new idea proves correct and can be extended to other planets with biospheres, it could increase the chances that earthly civilization finds extraterrestrial life by doubling the percentage of time that planets could be inhabited.

“[T]he Earth will be identifiable as an inhabited planet for nearly half the total lifetime of the Sun, an important point to consider in the search for life on extrasolar planets,” the authors write in the Proceedings of the National Academy of Sciences.

Over the next hundreds of millions of years, the sun will continue to get brighter until eventually, Earth becomes too hot to inhabit. Previous calculations had pegged that time at about a billion years from now, but the new paper argues that earlier models had neglected the role of atmospheric pressure in regulating the temperature of the planet on astronomical time scales.

Atmospheric pressure is a key variable in the overall greenhouse-gas effect because it determines how much infrared radiation greenhouse gases absorb. Higher pressures mean more absorption and consequently, more heat. Lower pressures have the opposite effect.

Life itself would be the mechanism for these temperature changes. By “fixing” nitrogen, pulling it out of the air and eventually into the Earth’s deep ocean, microbes could be making the atmosphere lighter one atom at a time.

“I am glad that Li and colleagues have raised the issue of how overall variation in atmospheric pressure may have affected past and may affect future climate,” ecologist Ken Caldeira of Stanford University said in an e-mail. “This could be relevant for understanding climate change on the billion-year time scale.”"

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Astronomy: Top Ten Hubble Scientific Discoveries

Hubble Telescope Image via Wikipedia

From Denny: Popular Science has a new article that is mostly awesome photos of what Hubble has captured over time! They explain the significance of each photo to the furthering education in astronomy. If you prefer a larger view, take a look at the slide show by clicking on the title link and it will take you to the Popular Science site. I love space photos like this!

So much of their article is the history of astronomy: how scientists thought about the universe, speculated and now they know for sure because of the Hubble Telescope. This is such a great summary article that I quoted it here in its entirety as a free source.



All Photos Courtesy of NASA

"10. The Source of Long Gamma Ray Bursts

In the 1960s, US satellites designed to detect gamma radiation from Russian nuclear testing began picking up huge radiation bursts from deep in space. For decades, no one knew where the bursts were coming from. When the Hubble went on line, scientists were able to track the gamma ray bursts back to galaxies with rapid star production, like the Large Magellanic Cloud galaxy (pictured). According to Livio, the gamma ray bursts occur when one of the galaxy’s massive stars collapses in on itself.



9. Accurate Measurement of the Hubble Constant

For years, scientists argued over the value of the Hubble Constant, a key component in the equation that measures the speed at which the universe expands. “Before the Hubble telescope, the estimates for the Hubble Constant were different by at least a factor of two,” said Livio. After analyzing Hubble pictures of far-off super novae (the remnants of one are pictured here), astronomers narrowed the value of the Hubble Constant down to within an error of five percent.



8. Stellar Populations

While some of the Hubble’s most notable pictures involved looking deep into space and time, it also made some important observations closer to home... if you consider 2.5 million light years close to home. Scientists knew very little about the histories of even our closest galactic neighbors (like the Andromeda galaxy shown here). But the Hubble, which can focus on individual stars in these galaxies, has allowed scientists to better understand the history of our corner of the universe.



7. Collision Images

Speaking of close to home, Hubble took one of its most important pictures of a planet right here in our own solar system. In 1994, fragments of the comet Shoemaker-Levy 9 hit Jupiter (pictured here), and Hubble provided the first ever recorded images of a collision between two bodies in space. Aside from simply looking cool, photos of the scars left by the collision provided new insights into the makeup of Jupiter’s atmosphere.



6. Counting Planets

Naturally, being the egocentric species that we are, contemplating the mysteries of the cosmos inevitably leads to the question of whether life exists on other planets. To answer that question, we need to know just how many other planets there are. Pictures from the Hubble went a long way towards answering that question. By capturing images of the solar debris disks that eventually coalesce into planets (like the disk shown here around a star in the Orion nebula), the Hubble showed that planets are far more common than scientists previously thought.



5. Extrasolar Planets

And while we’re on the subject of extrasolar planets, the Hubble also snapped the first shot of a planet outside of our solar system. Before this picture of a planet around the star Fomalhaut was taken, scientists had to calculate whether a star had a planet by evaluating the star's wobble. With the Hubble, the astronomers could just take a picture of the planet itself.



4. Black Holes

Astronomers had been theorizing that super massive black holes laid at the center of galaxies for years, but it wasn’t until the Hubble actually took a shot of one of those black holes that the debate was put to rest. “Not only did Hubble discover that there are black holes in the center of the galaxies, but it discovered that there was correlation between the size of the black hole and the size of the bulge,” said Mario Livio, a senior astrophysicist at the Space Telescope Science Institute and author of Is God A Mathematician?. “Before that, we did not know that there was a black hole in the center, and definitely did not know that relationship.”



3. Deep Field Shot

This is one of the cases where the aesthetic beauty of one of Hubble’s pictures matched up with its scientific value. The Hubble Deep Field Shot, the most magnified picture of a spot of the sky ever taken with optical light, provided this gorgeous image, and gave scientists the information they needed to accurately calculate the age of the universe.



2. Dark Matter

Long theorized and to this date never directly observed, dark matter may make up as much as 22 percent of the material in the universe. Because dark matter doesn’t reflect or emit light (hence the name), it cannot be viewed with a telescope. However, dark matter still exerts a gravitational pull on the light that passes by it, bending the light like a lens. The Hubble was able to take a picture of light bent by the gravitational lens of nearby dark matter, thus detecting the previously undetectable. This is a picture of light from the galaxy cluster Abell being warped by a gravitation lens from dark matter.



1. Dark Energy

According to the theory of General Relativity, the gravitational pull of every object in the universe would eventually slow, and then reverse, the expansion of the universe. For years, that’s what astronomers assumed was happening. Then came Hubble. “Arguably the most important Hubble discovery is that of dark energy, which is this form of energy that propels the expansion of the universe,” said Livio. “We knew since the late 1920s that the universe was expanding, but thought that this expansion would be slowing down. Instead, we discovered in 1998 that this expansion was speeding up.” This momentous discovery came from measuring light emitted by super novae, like the explosion of the star Sanduleak -69° 202a, pictured here."