Space at
your fingertips.
"I want to know why the universe exist, why there is something greater than nothing."
Steven Hawking
Scientist, Space Lover
Gleaming in the rays of the setting sun, boulders litter the rugged surface of asteroid 433 Eros. The brightest boulder, at the edge of the large, shadowy crater near this picture's bottom center, is about 30 meters (100 feet) across. In orbit around Eros since February 2000, the NEAR Shoemaker spacecraft's camera recorded the dramatic view earlier this month from an altitude of about 50 kilometers. Eros itself orbits the Sun with a perihelion of 1.13 Astronomical Units (AU) and aphelion of 1.78 AU. Part of a class of near-Earth asteroids, it spends much of its time between the orbits of Mars (at 1.5 AU) and Earth (at 1 AU) ... but it wasn't always that way. Eros and other near-Earth asteroids originally orbited in the main asteroid belt, between Jupiter and Mars. Over time, the gravitational influence of Jupiter and other planets perturbed their orbits sending them on trajectories closer to Earth.
A drop of water or prism of glass can spread out visible sunlight into a rainbow of colors. In order of increasing energy, the well known spectrum of colors in a rainbow runs red, orange, yellow, green, blue, indigo, violet. X-ray light too can be spread out into a spectrum ordered by energy ... but not by drops of water or glass. Instead, the orbiting Chandra X-ray Observatory uses a set of 540 finely ruled, gold gratings to spread out the x-rays, recording the results with digital detectors. The resulting x-ray spectrum reveals much about the compositions, temperatures, and motions within cosmic x-ray sources. This false color Chandra image shows the x-ray spectrum of a star system in Ursa Major cataloged as XTE J1118+480 and thought to consist of a sun-like star orbiting a black hole. Unlike the familiar appearance of a prism's visible light rainbow, the energies here are ordered along radial lines with the highest energy x-rays near the center and lowest energies near the upper left and lower right edges of the image. The central spiky region itself is created by x-rays from the source which are not spread out by the array of gratings.
What are these surface features on Titan? Scroll right to see the panoramic view captured last week by the Huygens probe as it descended toward Saturn's mysterious moon. Scientists are not yet sure what the above image is showing. On the far left, a boundary seems to exist between some sort of smooth dark terrain and a type of choppier terrain in the distance. In the image center and on the left, white areas cover the image that might be a type of ground fog. The Huygens probe landed in the dark area of the far right, finding a portion of Titan's surface that had the consistency of wet sand and a surface temperature of -179 degrees Celsius. Huygen's battery lasted an unexpectedly long three hours as it beamed back images and data to the Saturn-orbiting Cassini mothership and an armada of Earth's most sensitive radio telescopes. Analysis of the Huygens' images will likely continue for years in attempts to better understand this cloud-engulfed moon.
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