Category Archives: Kepler mission

exoplanets, exploration, Kepler mission

Planet Hunting Will Commence

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First Light for Kepler

Star Cluster NGC 6791 from Kepler First Light Image
NGC 6791 -- Kepler's first-light image. (Click to embiggen.)

Kepler, the planet-hunting satellite, has sent back its first light image —  a 100-square-degree patch of sky that contains a star cluster called NGC 6791. This is only a part of Kepler’s full field of view, but even from this image, it’s clear that Kepler has pretty good eyesight.

The Kepler spacecraft is equipped with a telescope and photometer, and is out there looking for planets like Earth and will be on the  hunt for the next 3.5 years.  It is focused on 100,000 pre-selected stars — and will continuously study their light output to watch for periods when these stars look a bit dimmer.  Such dips in brightness will be a very good indication that planets are crossing in front of the star, blocking out some of the light from their parent stars.

Kepler needs a very precise view to do this — and to be able to spot planets as small as Earth, the images are intentionally blurred slightly. This minimizes the number of saturated stars. Saturation, or “blooming,” occurs when the brightest stars overload individual pixels, causing the signal to spill out into nearby pixels.

The mission scientists and technicians for Kepler are now in a period of calibration and engineering testing, which will help astronomers tweak the focus and adjust its onboard instruments.  When that work is done, the serious work of planet-hunting will get started. It’s going to be a very exciting time for planet-hunters, who are already jazzed by the numbers of planets already found. But, Kepler gives them the chance to seek out Earth-type worlds — and who knows what they’ll find.  Stay tuned!

exoplanets, extrasolar planets, Keck Observatory, Kepler mission

About Those Exoplanets

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How Will We Know What Kepler’s Finding?

The galaxy neighborhood that Kepler will search for exoplanets. Courtesy Kepler Mission, painting by Jon Lomberg. (Click to embiggen.)
The galaxy neighborhood that Kepler will search for exoplanets. Courtesy Kepler Mission, painting by Jon Lomberg. (Click to embiggen.)

Now that the Kepler mission is on its way to final orbit and commissioning, astronomers are excited about the possibilities for new planets to be found “out there” in the nearest 3,000 light-years of space.  It’s worth remembering, however, that the Kepler spacecraft will be identifying planetary “possibilities” — that is, it will study star fields over time; in its data will be stars that appear to flicker.

The Kepler folk have a very cool interactive page that helps you understand how the spacecraft does its search (note, the link leads to a Flash-activated site), but essentially it looks for those flickers of star light and then relays that information to scientists for further study. There are thousands of stars to look at, so once Kepler commences on its official search mission, the datasets could be quite large. And who knows what we’ll find out there?

There are several possibilities about what causes stars to flicker, and only one of them is a planetary system.  A star could flicker because it’s variable – that is, it has some intrinsic (exclusive to itself) mechanism that causes its luminosity to brighten and dim on a regular schedule. All those stars will be of great interest to folks who study variables — including the American Association of Variable Star Observers.

Another possibility might be gravitational lensing events.  These occur when something  massive passes between us and a more distant object. Of course we’re familiar with gravitational lensing by distant galaxy clusters, but it can happen that something will do the same thing to a star in our own galaxy, causing its light output to appear to flicker. The late scientist Bohdan Paczy?ski was quite interested in such events, and the OGLE survey (among others) does real time studies of such events in our galaxy.

The Keck telescopes on Mauna Kea are used for planet-hunting. The Kepler mission findings will keep it busy searching out exoplanets. (Photo by Laurie Hatch, used by permission; click to embiggen.)
The Keck telescopes on Mauna Kea are used for planet-hunting. The Kepler mission findings will keep it busy searching out exoplanets. (Photo by Laurie Hatch, used by permission; click to embiggen.)

So, before Kepler scientists can confidently state that they’ve found a planet around another star, they have to take into account those other possibilities.

Once they think they’ve got a candidate, that’s when people like Geoff Marcy (of the University of California at Berkeley) step in and observe those stars using observatories such as the W.M. Keck telescopes in Hawai’i.

They essentially look for planets that are “transiting” the disks of the stars — that is, they pass in front of the star from our point of  view. That transit causes the flicker of starlight that betrays the existence of a planet.

The Keck team, headed by Marcy, will start looking for planetary candidates using Kepler data starting in late July of this year.  So, keep your eyes open for news from the exoplanet front. It’s bound to be interesting!