Fourier Analysis is a mathematical tool which can do a number of things: separate out signals from noise; help identify patterns or trends in data; filter out all unwanted data and focus on a single signal; use approximations to make generalizations; make approximations of real world signals (think electronic music); combine harmonics to get a stronger signal. That's what I'll be trying to do here!! Won't you join me with your comments?
Friday, August 10, 2007
15 reasons to Look at the Night Sky During August
2. The most prominent summer constellation is Sagittarius, the Archer, which in the Northern Hemisphere is seen in the southern sky . Look for the group of stars which seem to form the shape of a teapot.
3. When you are looking at Sagittarius, you are looking towards the center of the Milky Way Galaxy.
4. If you are fortunate to be in a "dark sky" location (meaning little or no light pollution from cities, highways, etc.) then you might notice what appears to be "steam" rising from the spout of the teapot. This is what is known as the Milky Way, the dense band of stars that are part of our galaxy.
5. To the right (West) of Sagittarius is the constellation Scorpio, the Scorpion. This is one of my favorite constellations to spot because it looks so much like its name. If you don't have many trees or buildings blocking the SW horizon, then you should be able to see the tail of the scorpion curled around about to sting! The bright star about where the heart or back of the scorpion would be is Antares and should have a red-orange color. Its brightness and color are similar to how the planet Mars appears in the night sky.
6. Looking up from the South towards overhead, you will see a very bright star. This is Vega in the constellation Lyra. It is one of the brightest stars that we can see.
7. Have you spotted Lyra? Now look to the left (East) about 40 degrees and a little above this star, and you should see another very bright star. This is Deneb in the constellation Cygnus (the Swan, which looks like a cross).
8. Look straight down from this star and you will find another bright star, Altair, in the constellation Aquila (the Eagle).
9. The 3 bright stars Vega, Deneb and Altair make up what is known as the "Summer Triangle". It is not one of the 88 official constellations, but has been used by sailors for navigation in the past.
10. If you want to try spotting a deep-sky object, go back to Sagittarius and look for the small triangle which is the teapot's lid. To the left of the top star in this triangle is a small "fuzzy" object, which looks almost like a cloud. Closer inspection with binoculars will show it is a cloud made up of stars. This is known as a globular cluster. (Use this term to impress your friends!) Whereas most of the stars we see in constellations only appear close to one another, in a globular cluster the stars really are close together. This deep-sky object is one of the brightest and one of the few we can see with the naked eye. And astronomically speaking, it is relatively close, only 10,400 light-years distant (that means it takes 10,400 years for light from this object to reach our eyes!)
11. Jupiter continues to be bright during this month, and appears as the "first star" in the southern sky after sunset. With a small telescope or strong binoculars, you should be able to see a couple of its moons!
12. If you can stay up late, Mars rises in the East after midnight. But the best view of it is early in the morning when it is highest in the sky. Look for a reddish-colored "star" that doesn't twinkle.
13. If you were not able to see the Delta Aquarids last month, my favorite meteor shower is coming up this month. This is the Perseid meteor shower. This shower is caused by the debris or dust from multiple visits of the comet Swift-Tuttle which has been left behind in the path of the Earth's orbit. As this debris enters the Earth's atmosphere, the dust burns up in streaks across the sky that we call meteors. It seem that the meteors are all coming from the constellation Perseus. Best viewing starts tomorrow night, Aug11-Aug14 and it should be spectacular as this year the moon comes up very late on these prime viewing dates.
14. For those of you living in the Americas, Australia and eastern Asia, you have a real treat in store on August 28th. This is the date of a lunar eclipse. Look at the moon during the eclipse period (this will vary depending on your location, but should be announced in the newspaper or on TV), and you should notice that the southern (lower) half of the moon looks brighter than the northern (upper) half. This is because the upper part of the moon passes deeper into the Earth's shadow, while the southern half will still receive light filtered through the Earth's atmosphere. There will not be any real boundary between the lighter/darker areas, but it might appear that the lighter area has a reddish tinge.
15. There is a new episode on "Amazing Space" which shows most of this information and more!
Wishing you fine summer weather, clear dark skies and happy viewing!!
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