NASA scientists have announced that they’ve detected carbon dioxide on a planet 63 light-years from Earth. Earlier research on this planet, which is called HD 189733b, discovered molecules of water vapor and methane gas. The new find is another technical triumph, part of a growing effort to measure the chemical makeup of faraway worlds.

Astronomers probe the composition of space objects with spectrometers. These devices split the light shining from or reflecting off the object into its spectrum, or component colors. These colors bear fingerprints of the elements that make up the object. Astronomers cannot directly see HD 189733b because it is too faint and “blinded” by the light of its host star. So the team, which was led by Mark Swain, a research scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, employed a visual trick to capture its light spectrum. They first scanned the light of the planet and its host star together using a spectrometer on the Hubble Space Telescope. They then scanned the star alone when the orbiting planet was hidden from view behind it. The difference between the two scans revealed evidence of carbon dioxide.

The find does not indicate that living things are producing carbon dioxide on HD 189733b. The planet orbits very close to its host star and thus is too hot to support life. Still, these chemical-tracing techniques may eventually find that life does exist outside of our Solar System.

Check out our animation of the discovery in the latest AMNH Astro Bulletin.

The rock that paves Mars's vast Arabia Terra region is very ancient and cratered. Now, the powerful HiRISE camera on the Mars Reconnaissance Orbiter has taken striking images of wind-eroded outcrops on some of the crater floors. The outcrops' sedimentary layers appear to have built up with rhythmic regularity, suggesting that random, catastrophic events such as floods or volcanic eruptions did not create them.

So what did? HiRISE's high-resolution images allowed Mars researchers to use investigative techniques practiced by Earth geologists. A team of scientists from the California Institute of Technology, the U.S. Geological Survey, and the University of Arizona reconstructed a 3D topographic map of a hilly region in Arabia Terra. They used this map to measure the height and pattern of the rock layers.

The results suggest that regular climate events built up the layers in stages. The best candidate for what would set off such cycles is the shift of Mars's tilt on its axis, which varies by a few degrees on a 100,000-year rhythm. These types of orbital changes on Earth induce periodic ice ages due to the planet's position relative to the Sun.

See more of HiRISE's images—including a movie of the 3-D map—in the latest AMNH Astro Bulletin.

At long last, two teams of scientists have directly glimpsed the feeble light of planets orbiting distant stars through the lenses of telescopes. Before now, all of the 325 planets discovered outside our solar system had been located by indirect means, such as measuring their gravitational effects on their host star. The two teams used enhanced optical techniques to bring the planets into view. One group, led by Paul Kalas of the University of California-Berkeley, used the Hubble Space Telescope to block the blinding light of the star Fomalhaut to resolve a planet orbiting in the star's surrounding disk of dust. The other group, a Canadian team led by Christian Marois of the Herzberg Institute of Astrophysics in British Columbia, saw not one but three planets around the star HR 8799. They used a method called adaptive optics to sharpen an Earth-based telescope image enough to spot the planetary system. Now, scientists can scan the light from these planets to learn what they are made of, their temperatures, and other intriguing details.

See more images behind the new discoveries in the latest AMNH Astro Bulletin.