Terrestrial Gallery

Solar System, artwork

Solar System. Artwork of Earth's solar system, showing the planets and other objects that orbit the Sun (upper right). The separations of the orbits are not shown to scale. Most of the mass of the solar system is found in the Sun. The planets, from inner to outer, are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Also shown here (beyond Neptune) is Pluto, a former planet now considered a large dwarf planet in the Kuiper Belt. The asteroid belt is shown between Mars and Jupiter. At upper left is a meteor shower, shown as it would appear from the Earth's surface as the meteors impact the atmosphere

© CLAUS LUNAU/SCIENCE PHOTO LIBRARY

Kepler-10b exoplanet, artwork

January 10, 2011
WASHINGTON -- NASA's Kepler mission confirmed the discovery of its
first rocky planet, named Kepler-10b. Measuring 1.4 times the size of
Earth, it is the smallest planet ever discovered outside our solar
system.
The discovery of this so-called exoplanet is based on more than eight
months of data collected by the spacecraft from May 2009 to early
January 2010.
"All of Kepler's best capabilities have converged to yield the first
solid evidence of a rocky planet orbiting a star other than our sun, "
said Natalie Batalha, Kepler's deputy science team lead at NASA's
Ames Research Center in Moffett Field, Calif. and primary author of
a paper on the discovery accepted by the Astrophysical Journal. "The
Kepler team made a commitment in 2010 about finding the telltale
signatures of small planets in the data, and it's beginning to pay
off."
Kepler's ultra-precise photometer measures the tiny decrease in a
star's brightness that occurs when a planet crosses in front of it.
The size of the planet can be derived from these periodic dips in
brightness. The distance between the planet and the star is
calculated by measuring the time between successive dips as the
planet orbits the star.
Kepler is the first NASA mission capable of finding Earth-size planets
in or near the habitable zone, the region in a planetary system where
liquid water can exist on the planet's surface. However, since it
orbits once every 0.84 days, Kepler-10b is more than 20 times closer
to its star than Mercury is to our sun and not in the habitable zone.
Kepler-10 was the first star identified that could potentially harbor
a small transiting planet, placing it at the top of the list for
ground-based observations with the W.M. Keck Observatory 10-meter
telescope in Hawaii.
Scientists waiting for a signal to confirm Kepler-10b as a planet were
not disappointed. Keck was able to measure tiny changes in the star's
spectrum, called Doppler shifts, caused by the telltale tug exerted
by the orbiting planet on the star.
"The discovery of Kepler 10-b is a significant milestone in the search
for planets similar to our own, " said Douglas Hudgins, Kepler program
scientist at NASA Headquarters in Washington. "Although this planet
is not in the habitable zone, the exciting find showcases the kinds
of discoveries made possible by the mission and the promise of many
more to come, " he said.
Knowledge of the planet is only as good as the knowledge of the star
it orbits. Because Kepler-10 is one of the brighter stars being
targeted by Kepler, scientists were able to detect high frequency
variations in the star's brightness generated by stellar
oscillations, or starquakes. This analysis allowed scientists to pin
down Kepler-10b's properties.
There is a clear signal in the data arising from light waves that
travel within the interior of the star. Kepler Asteroseismic Science
Consortium scientists use the information to better understand the
star, just as earthquakes are used to learn about Earth's interior
structure. As a result of this analysis, Kepler-10 is one of the most
well characterized planet-hosting stars in the universe.
That's good news for the team studying Kepler-10b. Accurate stellar
properties yield accurate planet properties. In the case of
Kepler-10b, the picture that emerges is of a rocky planet with a mass
4.6 times that of Earth and with an average density of 8.8 grams per
cubic centimeter -- similar to that of an iron dumbbell

© Detlev van Ravenswaay

Abingdon Island tortoise (Chelonoidis abingdoni)

Abingdon Island tortoise (Chelonoidis abingdoni). Lonesome George, last survivor of its species and icon for conservation efforts in the Galapagos Islands. He died on June 24, 2012 at an estimated age of 101 or 102 years old. Charles Darwin Research Station, Santa Cruz (Indefatigable) Island, Galapagos Islands, Ecuador

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