An Australian visitor wrote, I seek to find out what speed our sun is traveling at and also how many years it takes 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, 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, 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’s one of the loveliest stars you’ll ever see, Vega 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’s 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.
I was driving into work this morning, and in fact inside my company going due North. The moon was so large and just to the West. I suddenly realized the moon had a huge blue/grey shadow to its N. and a smaller shadow to its S. (same color). Also, it had a shadow on top kind of looking like a crown. At first I thought are we having a lunar eclipse? It was fairly low on the horizon about 30 degree’s above the horizon. It was beautiful, never seen anything like this, does anyone know what I was looking at. The time was about 6:55 am. I am in Indiana just at the tip of Lake Michigan.
Toni,
Was it before sunrise? If so, good chance you were looking at the Earth’s shadow. Oftentimes, you see the blue-grey shadow outlined by the purplish Belt of Venus. See the photo at http://apod.nasa.gov/apod/ap060723.html
Bruce
I like this one, illustrating “The Belt Of Venus”
http://stargeezeradio.com/starblog//wp-content/uploads//2010/06/belt-of-venus-pete-lawrence-selsey.jpg
[...] (EarthSky) An Australian visitor wrote, I seek to find out what speed our sun is traveling at and also how many years it takes to circumnavigate the galaxy. [...]
Estimates vary, but the sun is traveling around 140 miles per second. Even at this breakneck speed, it probably takes the sun some 230 million years to complete one revolution around the galactic center.
Bruce
It is 9:15pm in Bright Ontario. Clear sky. The moon is absolutely brilliant.
It is encompassed by huge white light and what seems to be rainbow colours around the bright white light of the moon, beginning in yellow to orange to reddish. I have never seen anything like this before, could it be a corona?
its 1:53 am in Trinidad,Caribbean and the moon has reached its highest point in the night’s sky. The slightly scattered clouds cover it, allowing the moon to glow through it like a foggy Halloween’s night. 30 degrees south-east from the moon, lies our stunning bright star- Sirius.