Sky Tonight—January 17, Sun moves toward star Vega in journey around galaxy
Posted By admin On January 16, 2011 @ 6:56 pm In Earth & Sky | Comments Disabled
Courtesy of EarthSky
A Clear Voice for Science
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www.EarthSky.org [1]
[2]
[3]An Australia visitor wrote, I seek to find out what speed our sun is traveling at and also how many years does it take to circumnavigate the galaxy?
Our Milky Way galaxy is a collection of several hundred billion stars. It has an estimated diameter of 100,000 light-years. Our sun does indeed circumnavigate the Milky Way galaxy. In space, everything moves. There are various estimates for the speed the sun travels through the galaxy [4], but its speed is about 140 miles per second.
Likewise, there are many estimates for the length of time it takes the sun to complete one circuit of the galaxy [5], but a typical estimate is about 230 million years.
That period of time, by the way, is known as a cosmic year. It so happens that astronomers know which star the sun is moving toward, in its journey around the galaxy. In January, this star appears in the west-northwest at dusk and nightfall. It also appears in the east-northeast at and before dawn in January. It is one of the loveliest stars you will ever see, Vega [6] in the constellation Lyra the Harp.
Our sun’s direction of motion (and thus our Earth’s corresponding motion) toward Vega has a special name. It has called the apex of the sun’s way. Vega – the solar apex star – can be found in the eastern sky during the dawn and predawn hours throughout January.
[7]Written by EarthSky [8]
Astronomy Picture of the Day from NASA/JPL [9]
EarthSky: Space [10]
CHANDRA Photo Album [11]
U.S. Naval Observator Astronomical Information cente [12]r
Universe Today [13]
StarDate Online [14]
Sky and Telescope [15]
National Geographic [16]
Space Com [17]
Simostronomy Blog [18]
Amazing Space [19]
The York County Astronomical Society [20]
Scope City [21]
Article printed from Recorder Online: http://www.berthoudrecorder.com
URL to article: http://www.berthoudrecorder.com/2011/01/16/sky-tonight%e2%80%94january-17-sun-moves-toward-star-vega-in-journey-around-galaxy/
URLs in this post:
[1] www.EarthSky.org: http://www.EarthSky.org
[2] Image: http://www.berthoudrecorder.com/wp-content/uploads/2011/01/phase17.gif
[3] Image: http://www.berthoudrecorder.com/wp-content/uploads/2011/01/jan17.jpg
[4] various estimates for the speed the sun travels through the galaxy: http://hypertextbook.com/facts/2001/AngelaChan.shtml
[5] estimates for the length of time it takes the sun to complete one circuit of the galaxy: http://hypertextbook.com/facts/2002/StacyLeong.shtml
[6] Vega: http://earthsky.org/tonightpost/brightest-stars/vega-brilliant-blue-white-is-third-brightest-star
[7] Image: http://www.berthoudrecorder.com/wp-content/uploads/2010/11/Earth-amp.png
[8] EarthSky: http://earthsky.org/author/Earth%20&%20Sky/
[9] Astronomy Picture of the Day from NASA/JPL: http://antwrp.gsfc.nasa.gov/apod/
[10] EarthSky: Space: http://earthsky.org/space
[11] CHANDRA Photo Album: http://chandra.harvard.edu/photo/
[12] U.S. Naval Observator Astronomical Information cente: http://www.usno.navy.mil/USNO/astronomical-applications/astronomical-information-center/astronomical-information-center
[13] Universe Today: http://www.universetoday.com/
[14] StarDate Online: http://stardate.org/
[15] Sky and Telescope: http://www.skyandtelescope.com/observing/ataglance/
[16] National Geographic: http://news.nationalgeographic.com/news/
[17] Space Com: http://www.space.com/nightsky/
[18] Simostronomy Blog: http://simostronomy.blogspot.com/
[19] Amazing Space: http://amazing-space.stsci.edu/tonights_sky/
[20] The York County Astronomical Society: http://www.ycas.org/tonights_sky.htm
[21] Scope City: http://www.scopecity.net/
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