Archive

Archive for June 13, 2012

One Ring to Bring Them All: Eclipse Enchants Grand Canyon

June 13, 2012 Leave a comment

Ever see ringlets of sunlight playing in the shadows of a tree or a fiery ring of light in the sky? These incredible effects are the results of an annular solar eclipse like the one that occurred when the moon passed directly between the sun and Earth on Sunday, May 20, 2012. The event was viewable from Japan all the way across the Pacific Ocean to midway through the United States.
Because the moon travels on a slightly tilted orbit compared to the plane of Earth’s orbit around the sun, eclipses do not occur every time the moon comes between the sun and Earth. However, there are two points or “nodes” when the moon does pass through this plane. If either of these nodes coincides with a new moon (when the sun is illuminating only its far side), a solar eclipse will occur. If a node is reached during a full moon, Earth will block the sun’s light, casting a shadow onto the moon causing a lunar eclipse.
An annular eclipse occurs when the moon is too far away from us to completely cover the disk of the sun. This results in an annularity: the ring-shaped outline of the sun that can be seen surrounding the dark new moon. Because of the surreal look of the “ring of fire,” annular eclipses are some of the most impressive celestial events visible from Earth.
This eclipse passed over some of the U.S.’s most famous national parks with the full annularity visible from 33 parks, while an additional 125 parks witnessed a partial eclipse. The NASA Lunar Science Institute (NLSI) at NASA’s Ames Research Center, Moffett Field, Calif., and the National Parks Service took advantage of this rare event and joined forces to facilitate safe viewings for as many people as possible.

Full Story: http://www.nasa.gov/centers/ames/news/features/2012/annular-eclipse.html

Astronomers pinpoint elusive galaxy after decade-long hunt

June 13, 2012 Leave a comment

An international team of astronomers led by Fabian Walter of the Max Planck Institute for Astronomy has managed for the first time to determine the distance of the galaxy HDF850.1, well-known among astronomers as being one of the most productive star-forming galaxies in the observable universe. The galaxy is at a distance of 12.5 billion light years. Hence, we see it as it was 12.5 billion years ago, when the universe was less than 10% of its current age. Even more of a surprise, HDF850.1 turns out to be part of a group of around a dozen protogalaxies that formed within the first billion years of cosmic history — only one of two such primordial clusters known to date. The work is being published in the journal Nature.
The galaxy HDF850.1 was discovered in 1998. It is famous for producing new stars at a rate that is near-incredible even on astronomical scales: a combined mass of a thousand Suns per year. For comparison: an ordinary galaxy such as our own produces no more than one solar mass’s worth of new stars per year. Yet for the past fourteen years, HDF850.1 has remained strangely elusive — its location in space, specifically: its distance from Earth the subject of many studies, but ultimately unknown. How was that possible?
The “Hubble Deep Field”, where HDF850.1 is located, is a region in the sky that affords an almost unparalleled view into the deepest reaches of space. It was first studied extensively using the Hubble Space Telescope. Yet observations using visible light only reveal part of the cosmic picture, and astronomers were quick to follow-up at different wavelengths. In the late 1990s, astronomers using the James Clerk Maxwell Telescope on Hawai’i surveyed the region using submillimeter radiation. This type of radiation, with wavelengths between a few tenths of a millimeter and a millimeter, is particularly suitable for detecting cool clouds of gas and dust.

Full Story: http://www.mpia.de/Public/menu_q2.php?Aktuelles/PR/2012/PR120613/PR_120613_en.html

Planets can form around different types of stars

June 13, 2012 Leave a comment

It had previously been thought that planets were more likely to form around a star if the star had a high content of heavier elements. But new research from the University of Copenhagen, among others, shows that small planets can form around very different types of stars — also stars that are relatively poor in heavy elements. This significantly increases the likelihood that Earth-like planets are widespread in the universe. The results have been published in the prestigious scientific journal, Nature.
3,000 exoplanets, i.e., planets orbiting a star other than the Sun, have now been discovered. 2,300 of these potential planets are being observed with the Kepler satellite by measuring the brightness of the host stars. If a planet moves in front of its star, there is a small decrease in the brightness and if this happens repeatedly, it could be a planet orbiting the star and dimming its light.
A multitude of planets have been discovered so far and by measuring their size it is possible to distinguish between gas giants like Saturn and Jupiter, or whether they are smaller, terrestrial planets like Earth and Mars.

Full Story: http://www.nbi.ku.dk/english/news

Astronomers Map 40 Million Stars

June 13, 2012 Leave a comment

Astronomers will soon have access to a new map of the sky that accurately measures the brightness and position of over 40 million stars.
This map is a result of the AAVSO Photometric All-Sky Survey, which has completely covered the sky at a level 100 times fainter than any prior stellar catalog. Millions of stars will have their brightness and color measured accurately for the first time in this survey.
“Prior surveys have done a good job measuring the brightness of bright stars. Other organizations have announced plans to measure faint stars. But this goldilocks zone of stars that are neither too bright or too faint has been neglected, until now,” Dr. Arne Henden, Director of the American Association of Variable Star Observers (AAVSO), said.
“This catalog of stars will serve a key link between existing bright catalogs and fainter catalogs planned for the future, such as those created by Pan-STARRS and the LSST observatories,” Dr. Doug Welch, a professor of Physics and Astronomy at McMaster University.

Full Story: http://aas.org/meetings/aas220