‘Twinkle, twinkle little star, how I wonder what you are.’ The words to that popular tune were written by Jane Taylor in 1806 and I bet there isn’t a person alive who hasn’t gazed up at the stars and sung that to themselves.
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Well we do know what stars are and a whole lot more. But stars don’t really twinkle! It’s an optical illusion.
If you were in space stars would be just bright, unblinking points of light. It’s our atmosphere which scatters the starlight before it reaches your eye, causing that ‘twinkling’ effect.
It also makes the familiar red, blue and green colour changes you see. Astronomers use this twinkling effect to calculate what the seeing is going to be like from one night to the next.
During September in Australia when you see a star low down on the horizon twinkling like crazy, you can bet it’s not going to be a good night for the telescope.
The atmosphere is too unsteady. Time to watch that video you’ve been putting off.
The next time you’re out stargazing, ponder this. By studying the skies, you are essentially staring into history, back into the distant past. The starlight you presently enjoy seeing takes hundreds, thousands and sometimes millions of years to reach us.
A lot of people still find it hard to distinguish a planet from a star. Remember this simple line, stars twinkle planets don’t.
The light from a star is generated by the star itself, appearing to “twinkle.” The light from a planet looks different, it’s reflected, shining steadily.”
Now, just after sunset, that bright ‘star’ you can see above the western horizon is really the planet Venus. Called the ‘goddess of love’ in Greek mythology, we know it better as the ‘evening’ and sometimes the ‘morning star,’ depending on the time of year. Either way its brilliance is overpowering.
Through a telescope Venus will show you phases just like the Moon, and you’ll notice it appears fuzzy. Well, that’s about as good as it gets, there’s nothing wrong with your telescope.
By the way, Venus is the number one object mistakenly reported as a UFO this time of year – true.
For a free 323 page astronomy e-book called ‘The Complete idiots Guide To Astronomy’ visit Dave’s website at www.davidreneke.com. Happy stargazing.
Dave Reneke, from Australasian Science Magazine
