Thursday April 17, 2014
What do you see if you look out at the universe? From Earth's surface, you see stars, planets, and galaxies. Of all these objects, galaxies are the most fascinating and evocative, but also tougher to spot in the sky than the others. Yes, there are a few naked-eye galaxies: the Andromeda Galaxy, and the Large and Small Magellanic Clouds. If you want to be complete, of course the Milky Way Galaxy is extremely easy to spot, but only because we're IN it. Most other galaxies are outside ours and they require magnification (binoculars and telescopes) if you want to see more than fuzzy blob of light. Astronomers have always seen many more galaxies with their larger research observatories, but nowadays, with the advent of advanced telescopes, such as Hubble Space Telescope, they're seeing a LOT more galaxies than they used to!
This image shows a galaxy cluster set against a backdrop of more distant galaxies. This is a remarkable cross-section of the universe, showing objects at different distances and stages in cosmic history. They range from cosmic near neighbors to objects seen in the early years of the universe. (See the Hubble web page for this story to view a larger image.)
Thursday April 17, 2014
Are you watching Cosmos: A Spacetime Odyssey? †In the U.S., it airs on Sundays on Fox TV and on Mondays on National Geographic Channel. You can also see episodes online at CosmosOnTV.com.†For space enthusiasts, astronomers, and others simply interested in learning more about our universe, this program is the one to see. It's the next generation of a series begun by Dr. Carl Sagan in 1980, a series that set a whole generation of astronomers and science writers on their career paths.
This new iteration of Cosmos is for the next generation of astronomers and writers, but really, it's for all of us. Astronomer Neil deGrasse Tyson is the host of the show, which is co-written by Ann Druyan and Stephen Soter. He's a good storyteller and has extensive background in astronomy and astrophysics. The stories he tells are tightly scripted, well visualized, and take viewers from Earth to the limits of the observable universe, from the science of today to the science of pre-history. A recent episode called A Sky Full of Ghosts taught us about the electromagnetic spectrum, and the information about distant objects hidden in the light they emit or reflect.†It featured an animation of the venerable English astronomer Sir William Herschel, walking on the beach with his son John (who later became an astronomer). The voice was supplied by the English actor†Sir Patrick Stewart, a nice touch.
Tuesday April 15, 2014
Cassini Spots a New Object in Saturn's Rings
If you're out stargazing over the next few months, at some point, you will notice the planet Saturn. On these April nights, it's rising late in the evening (right now around 10 p.m. or thereabouts), so you have to stay up to find it. But, it's well worth the look. The rings alone give this planet an otherworldly and fascinating appearance.
Those of us who gaze at Saturn from our backyards aren't the only ones watching this planet. The Cassini spacecraft, which has been studying the Saturn system since 2004, has been our eyes, ears, and planetary science exploring, sending back incredible images and data. †It has sent the Huygens probe to the surface of Saturn's largest moon, Titan, returning amazing information about this weird world. Cassini has also found an ocean of salty water beneath the icy surface of the moon Enceladus, mapped the rings, and shown us the beauty of Saturn's ever-changing cloud tops. Recently, it documented the formation of a small icy object within one of the planet's outermost rings. It could be a new moon, forming from the chunks of ice that orbit Saturn and form its rings.
A possible new moon of Saturn, discovered as part of a disturbance in Saturn's outermost A ring. Courtesy NASA/JPL-Caltech/Space Science Institute.
The object shows up in images taken with Cassini's narrow angle camera on April 15, 2013, and shows disturbances at the very edge of the A ring. One of these disturbances is an arc about 20 percent brighter than its surroundings, 750 miles (1,200 kilometers) long and 6 miles (10 kilometers) wide. Scientists also found unusual features in the usually smooth profile at the ring's edge. It's likely that the arc and its features are caused by the gravitational effects of a nearby object.
Friday April 11, 2014
How the April 14-15, 2014 lunar eclipse could look during totality. The Moon will be near the bright star Spica. Created by Carolyn Collins Petersen using Stellarium open source software. Click image for a larger version.)
Experience a Total Lunar Eclipse!
On April 15th, in the wee hours of the morning, you have a chance to see one of nature's most awe-inspiring events: a total lunar eclipse. People are referring to this one as a Blood Moon because at totality (the darkest part of the eclipse), the Moon will appear a deep red color. Observers across the Americas, and parts of the Pacific will able to witness it beginning late Monday night April 14 into the early morning of April 15th. (For a complete list of what locations on Earth will see this eclipse, check out NASA's Eclipse Web page.)
What You Will See
So, what is a lunar eclipse? These rare events happen at†Full Moon, when the Moon moves into Earth's shadow as it orbits our planet. The entire eclipse takes almost 6 hours (5 hours 43 minutes). First, it slips into the penumbra at the western edge of the shadow. At first, you won't notice much because the Moon is still quite bright. Then, about an hour later, the Moon will begin entering the†umbra, the darkest part of Earth's shadow. This is when you will start to notice the Moon slowly taking on color -- anywhere from a ruddy brown to a coppery red. †The Moon will spend just over an hour (1 hour 17 minutes) in the umbra. Then it will slowly move out into the eastern part of the penumbra, and finally exit Earth's shadow completely.
When Should I Look?
Here's a short timeline of events. Times are approximate.
The eclipse begins at 4:53 AM UT (April 15) 12:53 AM EDT, 11:53 AM CDT (April 14th), ¬†10:53 PM MDT, 9:53 PM PDT, 6:53 PM Hawai'i time.
Totality begins at 7:08 AM UT (April 15), 3:08 AM EDT, 2:08 AM CDT, 1:08 AM MDT, 12:08 AM PDT, 9:08 PM Hawai'i (April 14)
Totality ends at 8:23 AM UT (April 15), 4:23 AM EDT, 3:23 AM CDT, 2:23 AM MDT, 1:23 AM PDT, 10:23 PM Hawai'i (April 14)
Eclipse ends at 10:35 AM UT (April 15), 6:36 AM EDT (below horizon), 5:35 AM CDT, 4:35 AM MDT, 3:35 AM PDT, 12:35 AM Hawai'i
A timeline of the April 14-15, 2014 lunar eclipse, based on data from NASA. Click image for a larger version.