Hubble snaps an image of ISON.
NASA has released a stunning photo of Comet ISON against a background of stars and distant galaxies. The composite image was stitched together from five photos snapped by the space agency’s Hubble Space Telescope on April 30, 2013.
According to scientists, the five photos were captured by Hubble’s Wide Field Camera 2 UVIS instrument. Three exposures were taken with a filter that transmits yellow and green light (seen as blue in the image) and two used a filter that let in red and some infra-red light.
“The result is part science, part art,” blogged Josh Sokol of the Space Telescope Science Institute in Baltimore, Maryland, which operates Hubble. “It’s a simulation of what our eyes, with their ability to dynamically adjust to bright and fainter objects, would see if we could look up at the heavens with the resolution of Hubble.”
Sokol explained that in other ISON observations, scientists have pointed Hubble at the comet as it traverses across a starry backdrop. While this technique works well for getting an image of ISON, it does not do a good job capturing the fainter stars and galaxies that illuminate the comet’s celestial highway. So, scientists settled for a trade-off by keeping Hubble trained on the stars as it snapped pictures of the comet.
Comet ISON is hurtling toward the sun on a trajectory that started 10,000 years ago in a distant region of space known as the Oort Cloud. On November 28, Thanksgiving Day, the comet will pass just 724,000 miles (1.16 million kilometers) the the solar surface. If it survives its perilous odyssey through ever-increasing solar radiation and tidal forces, it could illuminate the heavens for weeks and appear brighter than the moon, say astronomers. At the time of this latest image, ISON was located somewhere between Jupiter and the Asteroid Belt.
The comet, with a nucleus of about 3-4 miles in diameter, is known as a sun-grazing comet because its orbit brings it so close to the sun. As it plunges toward the inner solar system, the comet’s icy nucleus heats up and plumes of vapor rise off its surface and carry away more than 200 million kilograms of microscopic dust particles each day. The size of the comet’s tail, a ribbon of gas and dust coming off its frozen nucleus, also will increase beyond its current length, which at present could wrap around the Earth a staggering seven times.
Comet ISON was discovered by Russian astronomers Vitali Nevski and Artyom Novichonok in September 2012. It is named after a telescope for the International Scientific Optical Network (ISON), a group of observatories in 10 nations designed to track objects in space. Scientists believe the comet is making its first-ever trip to the inner solar system from the far-away region of the Oort Cloud.