1. Light from distant stars and galaxies takes so long to reach - TopicsExpress



          

1. Light from distant stars and galaxies takes so long to reach us, that we are actually seeing objects as they appeared hundreds, thousands or even millions of years ago. So, as we look up at the sky, we are really looking back in time. 2. The Crab Nebula was produced by a supernova explosion in 1054 A.D. The Chinese and Arab astronomers at the time noted that the explosion was so bright, that it was visible during the day, and lit up the night sky for months. 3. Shooting stars are usually just tiny dust particles falling through our atmosphere. Comets sometimes pass through Earth’s orbit, leaving trails of dust behind. Then as Earth plows through the dust in its path, the particles heat up, creating the streaks in the night sky. 4. Even though Mercury is the closest planet to the Sun, temperatures can reach -280 degrees F. Why? Since Mercury has almost no atmosphere, there is nothing to trap heat near the surface. So, the dark side of Mercury (the side facing away from the Sun) is very cold. 5. Venus is considerably hotter than Mercury, even though it is further away from the Sun. The thickness of Venus’ atmosphere traps heat near the surface of the planet.
Posted on: Sat, 07 Sep 2013 05:05:27 +0000

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