April 1, 2011
The Keck I Telescope has played a key role in unraveling the mysteries of one of the brightest supernovas ever discovered. Supernova 2008am is 3.7 billion light-years away from Earth. At its peak luminosity, it was over 100 billion times brighter than the Sun. It emitted enough energy in one second to satisfy the power needs of the United States for one million times longer than the universe has existed. In-depth studies of this supernova, including images from the Keck I Low Resolution Imaging Spectrometer (LRIS), are helping a team of astronomers to understand the science behind this new class of exploding stars. Read the rest of the story at http://www.keckobservatory.org/images/site/recent/entry/keck_telescope_images_super_luminous_supernova
THIS WEEKEND: TURN ON THE STARS
Help chart the darkness, or light pollution, of Earth?s skies this weekend by becoming a citizen scientist for the GLOBE at Night campaign. It?s easy and you can do it from just about anywhere on Earth. All you need is access to the sky, the Internet and a pair of eyes. If your eyes don?t work very well, recruit your children or grandchildren to help. There are family-oriented activity packets, web apps and other resources that make it a snap to help keep the night dark at http://www.globeatnight.org/
NO (APRIL) FOOLING: SUPER MOON FACTS & FICTIONS
Recently the Moon appeared larger in the sky than it has for about 20 years. The scientific explanation for this is simple. But the tall tales and myths that hitch along with the Super Moon are many and varied. If you are still a little confused about Super Moons, here is a short primer:
Fact: The Super Moon is caused by the elliptical orbit of the Moon, which means there is an approximately 30,000 mile (50,000 km) variation in the distance of the Moon to Earth every month. When the closer part of the orbit, called the perigee, coincides with a full moon (which is not often, as the perigee point changes all the time), the Moon naturally appears a bit larger in the sky. In the recent March Super Moon case, some scientific sources calculated the Moon appeared 14 percent larger and 30 percent brighter.
Fiction: The Super Moon triggers earthquakes.
Fact: Geophysicists have found little in the way of statistically significant connections between quakes and full moons or lunar perigees. They also point out that the tectonic forces which produce most earthquakes are many orders of magnitude stronger than the gravitational variations exerted on the Earth?s crust by the Moon.
Fiction: When a full moon rises, it appears larger because of the magnification effects of shining obliquely through Earth?s atmosphere.
Fact: This is known as the Moon Illusion. There is no magnifying effect. Anyone can prove this by measuring the diameter of the Moon when it is rising, using fingers at arm?s length, then doing the same thing a few hours later when the Moon is higher in the sky. The Moon?s diameter is unchanged. Just why a full moon appears larger near the horizon is not clear, but it likely has something to do with the way the human brain processes the image of the Moon when it is closer to other objects.
That brings us to another kind of Super Moon, which could even be called the Super Illusion Moon. This happens when a full Moon coincides with a very southerly or northerly Moon orbit (the Moon?s orbit does not chart a neat ring around the Earth?s equator, but swings well above and below the equator too, sort of like a hoolahoop). As a result, a full moon can appear to cross the sky much closer to the horizon, causing the Moon Illusion to last all night.