When you look up into the sky on a moonless night, you see even more stars than you think. That’s because about 75 percent of the ‘stars’ you see are actually groups of two, three, or more stars orbiting around each other.
Category: Astronomy
The Discovery of Helium
Helium was discovered in spectral analysis of the sun 14 years before anyone realized it also exists on the earth.
Seeing Back Billions of Years
Scientists estimate that the universe is 15 billion years old. By looking far out into space, they can see the past in other places, because light takes time to reach us. An event that happened on the sun nine minutes ago will just be now visible to us. Astronomers have recently discovered a place so far away that it dates back to almost the beginning of the universe. What we see today happened 14 billion years ago.
Radio Waves and Snowflakes
In a 1980 television show, popular astronomer Carl Sagan said, “All of the radio waves from space ever studied equal less than the power of a single snowflake hitting the ground.”
That wasn’t quite true then, but it was close. Today, with many more radio telescopes and many more years of collecting astronomical radio waves, the total power of all the waves studied from space is still much less than the energy your body used while you read this post.
Sunspot Activity
During major sunspot activity, compass readings can be inaccurate by as much as ten degrees.
Solar Hurricanes
On the sun there are hurricanes bigger than 100 Earths.
Solar Flares
Solar flares can reach more than 100,000 miles (160,000 km) away from the sun.
Moon Rocks
There are now 843 pounds (382 kg) of moon rock on earth. Roughly as much as would fill the trunk of an average size car.
Moon Landing
When astronauts landed on the moon, their instruments noticed that because of the impact of their landing, the moon rang like a bell for fifty-five minutes.
Orreries
I’ll bet you don’t know what an orrery is! It is one of those things you see in museums that model the solar system. The sun and the planets are made out of various size balls held on wires, and they circle around like the hands of a clock.
Orreries are hopelessly out of scale. In reality, if the sun was three feet (one meter) in diameter, the earth would be the size of a pea. The pea would be circling the three-foot sun on a wire 100 feet (30 meters) long. This whole thing, with the pea-size earth, and with all the other planets would be over ninety miles (145 kilometers) in diameter.
