Sometimes I complain about the earthly weather, but mostly I like to post about astronomy and space events. Hope you enjoy the articles.
By: Susie77, 3:42 PM GMT on April 25, 2013
Courtesy of Science @ NASA
See Saturn at its Best and Brightest
April 25, 2013: The Solar System is a beautiful place filled with wonders that NASA space probes are only beginning to discover. There's a tendency, though, for people to become indifferent; every year Hubble, Cassini, MESSENGER and other spacecraft beam back gigabytes of jaw-dropping images. After a while, you don't have any more "gasps" left in you.
Well, maybe just one more. Inhale deeply, because at the end of April, Saturn will put on a breathtaking display.
No space probe is required to see it. Just set up a telescope in your back yard--even a small department store ‘scope will do--and point the optics toward the constellation Virgo. Saturn is there, not far from the bright star Spica.
On April 28th, Saturn makes its closest approach to Earth, appearing bigger and brighter than at any other time in 2013. Astronomers call this event "an opposition," because Saturn will be opposite the sun in the skies of Earth. The golden planet rises at sunset, soars almost overhead at midnight, and stays up all night long.
Observers who see Saturn for the first time through the eyepiece of a telescope often gasp. The view is Hubble-esque, but the experience is much more personal. You’re seeing Saturn with your own eyes, a celestial wonder right out of the pages of an Astronomy magazine. The sight of that cloudy sphere suspended in the middle of crisp, thin icy rings is almost unreal.
To the naked eye, Saturn at opposition is about twice as bright as a first-magnitude star. This makes it relatively easy to find. Novices should start looking on April 25-26, when the full Moon passes Saturn only a few degrees away. For that one night, the Moon will act as a beacon, guiding observers straight to the ringed planet. Once you know where Saturn is, you can find it again on subsequent nights.
Look again on April 28th. That's when Saturn will be closest to Earth--about 1.3 billion km away. If clouds intervene, don’t worry; there are many more opportunities to look. Saturn will remain a golden jewel in the midnight sky for weeks to come.
Meanwhile, NASA's Cassini spacecraft is circling Saturn, exploring the planet and its environment at point-blank range. Since it reached the Saturn system in 2004, Cassini has found a moon with “tiger stripes” spewing geysers of salty water; an electrical storm big enough to swallow Earth; methane lakes and rain on Titan; braids, spokes and other strange ripples in Saturn's rings; a hexagonal cloud system surrounding Saturn's north pole; a satellite that looks like a sponge, and much more.
Saturn is near. Save the indifference for another planet!
Author: Dr. Tony Phillips | Production editor: Dr. Tony Phillips | Credit: Science@NASA
By: Susie77, 12:20 AM GMT on April 22, 2013
Courtesy of Space Weather
Every year in late April Earth passes through the dusty tail of Comet Thatcher (C/1861 G1), and the encounter causes a meteor shower--the Lyrids. This year the shower peaks on Monday morning, April 22nd. Forecasters expect 10 to 20 meteors per hour, although outbursts as high as 100 meteors per hour are possible.
Lyrid meteors appear to stream from the bright star Vega in the constellation Lyra:
In fact, Lyrids have nothing to do with Vega. The true source of the shower is Comet Thatcher. Every year in April, Earth plows through Thatcher's dusty tail. Flakes of comet dust, most no bigger than grains of sand, strike Earth's atmosphere traveling 49 km/s (110,000 mph) and disintegrate as streaks of light.
Lyrid meteors are typically as bright as the stars in the Big Dipper, which is to say of middling brightness. But some are more intense, even brighter than Venus. These "Lyrid fireballs" cast shadows for a split second and leave behind smokey debris trails that linger for minutes.
Occasionally, the shower intensifies. Most years in April there are no more than 5 to 20 meteors per hour during the shower's peak. But sometimes, when Earth glides through an unusually dense clump of comet debris, the rate increases. Sky watchers in 1982, for instance, counted 90 Lyrids per hour. An even more impressive outburst was documented in 1803 by a journalist in Richmond, Virginia, who wrote:
"Shooting stars. This electrical [sic] phenomenon was observed on Wednesday morning last at Richmond and its vicinity, in a manner that alarmed many, and astonished every person that beheld it. From one until three in the morning, those starry meteors seemed to fall from every point in the heavens, in such numbers as to resemble a shower of sky rockets..." [ref]
What will the Lyrids do this year? The only way to know for sure is to go outside and look.
Experienced meteor watchers suggest the following viewing strategy: Dress warmly. Bring a reclining chair, or spread a thick blanket over a flat spot of ground. Lie down and look up somewhat toward the east. Meteors can appear in any part of the sky, although their trails will tend to point back toward the radiant--i.e., toward Vega.
Vega is a brilliant blue-white star about three times wider than our Sun and 25 light years away. You might have seen Vega in Carl Sagan's movie Contact. It was the source of alien radio transmissions to Earth.
By: Susie77, 3:11 PM GMT on April 13, 2013
[I wrote this on Thursday, in memory of my son-in-law's father, who was killed while repairing electrical service following the tornadoes in St. Louis on Wednesday evening.]
You were always on-call, day or night, no matter how horrible the weather. You were up on the pole before the rain even stopped, restoring power so we could have our boobtube and cell chargers and computers. When Katrina destroyed N.O., you left home and drove 900 miles and stayed for weeks in the sweltering humidity to get the power back on. When Sandy hit, you drove 1000 miles to help out there, staying in Red Cross shelters and paying for your own meals. You were smart and funny. You had the best facebook cartoons and jokes. You loved your family more than life.
You died today, restoring power to people who lost it during the tornadoes last night. We will miss you, David. Requiescant in pace.