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Showing entries for Category: aphelion
Fireworks, planets, and stars - Oh My!
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What we hope to see!
Well, hope springs eternal. Sometimes we actually get a clear night and the fireworks show is visible from all over the city. Although the fog prediction for this evening doesn't look promising, it suggests that the Northeast quadrant of the city - which includes the fireworks launch site down by Pier 39 - could be clear of fog during the event, which will start at about 9:30 PM and last about half an hour.
If the fog has a total grip on the city, you can always enjoy a virtual fireworks show in the comfort of your own home.
Looking West (Image by Stellarium)
In case it is clear where you are (and since you will be looking in the general direction of the sky anyway), you might note that the ongoing fireworks show that is the cosmos has thrown up a few sparklers of its own this evening.
To the West, close to the horizon, emerging from the glow of the setting sun, is a fine triple of bright lights made up of Saturn, Mars, and the star Regulus in the constellation Leo, descending from upper left to lower right in that order. The new Moon will be a very thin crescent setting about an hour after the Sun. High in the sky, the brightest star is Arcturus, in the constellation Bootes (follow the arc of the handle of the Big Dipper).
Looking Southeast (Image by Stellarium)
To the East, Jupiter is the bright light relatively close to the horizon a bit south of East. Pretty much straight East, and a little higher in the sky is the star Altair, in the constellation of Aquila, the Eagle. Higher still in the sky, in the constellation Lyra, is the bright star Vega, while Deneb, in Cygnus, is a little lower in the sky, and a little further to the North.
Fireworks manufacturers try to time the display burst to coincide with the rocket's peak altitude. Coincidentally, the Earth today reached the "peak altitude" of its orbit around the Sun: the "aphelion" point. It's closest approach to the sun - "perihelion" - will take place January 4th, 2009.
The actual difference in our distance from the Sun is only about 1/30th of the radius of our orbit, so being closer to, or farther away from, the Sun doesn't affect the temperature of our planet very much. It does, however, affect the length of the seasons, as the Earth travels slower when it is further from the Sun. Hence, summer lasts longer than winter (in the Northern Hemisphere anyway.)
Further Information
SF Bay Area Fog Forecast
SF Bay Area Wind Patterns
The Physics of Fireworks
How Fireworks Work
Cyber-Fireworks
Stellarium is an excellent free planetarium program for your computer.
Aphelion articles can be found here and here
Topics: science , fireworks , aphelion , perihelion
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