Friday 25 October 2013

NASA

Nasa publishes many astronomical photographs. Here is one photograph taken from the International Space station of Great Britain and Ireland. 
 
Cities such as London, Birmingham Manchester, Glasgow, Edinburgh and Dublin can be picked out with ease.
So next time you go out, don't forget to turn out the light.

Often the images we see are of deep space objects from the Hubble telescope.

Many of the objects imaged are hundreds of light years distance. The colours are stunning and the scale is almost unimaginable. Where the vast distances are calculated in units of light years. A light-year is an astronomical unit of length equal to just under 10 trillion kilometres or 6 trillion miles.
 
The light-year is most often used when expressing distances to stars and other distances on a galactic scale. Especially in non-specialist and popular science publications. Like computer science uses units in binary counting in '2' or hexadecimal counting in '8' The preferred unit in astrometry is the parsec or '3.26 light-years' Used as it can be more easily derived from and compared with observational data. The light-year is a measure of distance, not of time.
The image above is of the Andromeda Galaxy (Messier 31) which is a similar sized galaxy to our own. Often used as an example of what the milky way would look like if we were on a planet in the Andromeda galaxy.
 
However, If the latest research is correct, then the actual shape of the Milky Way would be much more similar to what is known as the Great Barred Galaxy, affectionately known to astronomers with the catchy name of NGC 1365. If that is the case then what our galactic home looks like would be much more like this.

If the latest paper is correct, then the actual shape of the Milky Way would be much more similar to what is known as the Great Barred Galaxy, affectionately known to astronomers as NGC 1365. If that is the case then what our galactic home looks like would be much more like this. - See more Click Here


Light from the moon takes about 1 second to reach us. Light from the sun takes 8.3 minutes to arrive here. Earth is located about 27,000 light-years away from the galactic centre. Our galaxy is called the Milky Way and is estimated to be some 120,000 light-years in diameter.

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