Time lapse video of Winter Solstice Lunar Eclipse on December 21, 2010. This was shot from Gainesville, Florida.
And here’s how last night’s eclipse helped astronomers in the search for extraterrestrial life:
As Earth slips between the sun and moon, changing the tint of the lunar surface from white to orange to russet and back, you’re seeing the effect Earth’s atmosphere is having on the color of sunlight passing through it. But the atmosphere is doing something else. It’s in effect tagging the sun’s rays with the chemical fingerprints of gases in the atmosphere
Over the past two years, two teams of astronomers have been using this effect to figure out what Earth might look like as a distant, extrasolar planet orbiting another star. By analyzing the light reflected off the moon during a lunar eclipse – light that has passed through Earth’s atmosphere – they have detected gases in the atmosphere that indicate the presence of organic life on the planet.
If the teams’ baby steps are any indication, the techniques they are developing may be able to detect evidence of organic life imprinted in an extrasolar planet’s atmosphere – at least for rocky, Earth-mass planets orbiting stars relatively close to the sun – using large Earthbound telescopes.
“It’s an exciting experiment – one of the few I’ve seen that I wish I’d thought of myself,” says Sara Seager, a physicist at the Massachusetts Institute of Technology who studies exoplanets and their atmospheres and who was not involved in either project.
“The Earth is our best laboratory; it’s the only planet we know of with life,” she says. “So we really want to understand what Earth would look like as an exoplanet far away.”
Of special interest are planets whose orbits carry them in front of their parent stars as seen from Earth – so-called transiting planets.
These are the types of extrasolar planets NASA’s Kepler spacecraft and the French Space Agency’s CoRoT spacecraft currently are hunting.
Kepler in particular is searching more than 150,000 stars for Earth-mass planets in their stars’ so-called habitable zones. These are regions of space close enough to a star that liquid water would be stable on the surface of a planet orbiting at that distance.
NASA astrobiologists have discovered a microorganism in California that is doing something completely novel: substituting arsenic for phosphorus in its chemical makeup.Carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur are the six basic building blocks of all known forms of life on Earth. Phosphorus is part of the chemical backbone of DNA and RNA, the structures that carry genetic instructions for life, and is considered an essential element for all living cells. Arsenic, which is chemically similar to phosphorus, is poisonous for most life on Earth. Arsenic disrupts metabolic pathways because chemically it behaves similarly to phosphate.
It’s been known for a while that some microbes can metabolise arsenic, but what this organism is doing is building parts of itself out of arsenic, something no other known life forms can do. ”If something here on Earth can do something so unexpected,” asks Felisa Wolfe-Simon, a NASA Astrobiology Research Fellow, “What else can life do that we haven’t seen yet?”
This will change the way astrobiologists look for life on other planets, including where they look (arsenic-rich atmospheres were previously considered off-limits) and what the definition of life really is (right now, we only know that life exists the way it does on Earth, so finding out that life can exist very differently and using different chemicals will expand what we think of when we think of “life”). This is the first alternative biology we’ve ever known to exist; previously, the idea of alternative biologies has been mere speculation, more common in the realms of pop-science and science fiction.
ALTHOUGH THE COMMON ANCESTOR OF SEA ANEMONES AND HUMANS WOULD LOOK NOTHING LIKE US, IT STILLSHARES ONE OF OUR BASIC TRAITS: THE CAPACITY TO EXPERIENCE JET LAG.
At first glance, a sea anemone doesn’t seem much like a human. It’s a creature from the tidal zone, affixed to the rock or coral below, and without most of the anatomical features associated with humankind: It has no arms, legs, ears, eyes, or nose. It almost seems more like a plant than an animal. Anemones don’t even have a brain; instead their nerves form a network distributed throughout the body; each nerve cell can communicate with its neighbors, but no central structure controls the entire organism.
But a study published last month shows that anemones share one trait with humans: They, like us, are susceptible to jet lag. Like humans, anemones have a strong circadian rhythm, an activity cycle kept on a roughly 24-hour period by built-in biological clocks. It’s your circadian rhythm that contributes to feeling groggy at night and alert during the day. The study, led by Adam Reitzel, was discussed both on It Takes 30, the blog of the Harvard Systems Biology Department, and Dormiviglia, by Allison Brager, a physiology graduate student specializing in circadian rhythms.