Your Night Sky

The Eta Aquarid meteor shower is coming up this month, and will peak on the morning of May 5 & 6. You can start looking for them now. They are more prominent in the southern hemisphere, but we’re far enough south to have a good view. There are generally 20-50 per hour at the peak. The full moon is on the 10th, but will set early enough on these mornings so as not to interfere with your viewing.
They seem to radiate from the Aquarius constellation which is to the right of the Great Square of Pegasus in the eastern ski around 4 a.m. What’s special about these meteoroids is that they hit our atmosphere at 41 miles per second, which is one of the fastest velocities. That combined with their low trajectory generally gives them long tails as they travel through the sky. So they’re worth getting up early for.
While you’re looking in the east, you will see bright Venus shining low in the sky. Venus is often called Earth’s Sister planet. It’s similarly composed of silicate rock and metals which are divided between a metal core and a silicate crust and mantle. It also orbits within the Sun’s habitable zone and has a similar violent volcanic past.
But that’s where it ends. Venus’s atmosphere is incredibly dense and is 92 times thicker than ours. This holds the heat and causes its surface temperature to be 863 degrees F. That’s hot enough to melt lead. This toxic choking atmosphere of super heated CO2 would crush us if we tried to stand on Venus.
It also prevents us from seeing its surface. From 1975 to 1984 the Soviet Union sent many space craft to explore Venus. They had to go through the atmosphere to take pictures. The early ones only lasted about 50 minutes and the last one survived a little more than 2 hours. Nothing has been back on the planet since then.
What makes Venus so bright are its clouds of sulfuric acid that reflect the sunlight and make it glow. About 90 percent of the sunlight gets sent back into space. It’s also the second planet from the Sun making it relatively close to us. There have been flybys and atmospheric probes that have explored its atmosphere. Only radar instruments can penetrate its dark clouds.
Venus is isothermal which means there is very little variation in its surface temperature between day and night, its equator and poles, or seasons. Only altitude varies its temperatures. It has 2 high altitude continents, one at the northern hemisphere and one just below the equator. Together they equal 20 percent of its surface. The northern one is about the size of Australia and has the highest mountain on Venus, which is 7 miles high. The other one is about the size of South America.
Its wind can be as high 186 MPH, which makes the cloud tops circle the planet every 4-5 days. This is interesting because Venus has a very slow rotation that equals 247 Earth days. This is the slowest rotation of any planet. It also takes 224.7 Earth days to make one orbit around the Sun. So the wind is faster than Venus is moving, and a day is longer than a year on Venus. To give you an idea, its equator rotates at 4.04 MPH as opposed to Earth’s which rotates at 1,037.6 MPH.
The last interesting Venus fact this week is that it’s the only planet that orbits the Sun clockwise, which is the reverse of every other planet. This is called retrograde rotation. So on Venus, the Sun rises in the west and sets in the east. Also, Venus and Mercury are the only planets that do not have any moons. There will be many more interesting facts about Venus next week.


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