Last night, I turned my telescope to the constellation Lyra. It's northeast at this time of the year and you can't miss it because it'll have the brightest star in that part of sky - Vega. In fact, Vega is the second brightest star in the northern celestial hemisphere, after Arcturus. One of the reasons why it's so bright is because it's relatively close to us - only 25 light-years away from Earth. It's also three times the size of our sun and about 58 times more luminous.
If you've ever wondered why stars are always depicted in drawings as having points (five usually), a clear illustration of this can be seen in the video I took of Vega:
And below is a still from one of the frames of the video - sure looks like a star to me!
Stars are suns and hence spherical. Bright spheres viewed from afar should theoretically just look like steady dots or pin pricks of light. So why do stars twinkle and appear to have points? If you look at a really bright star, you will indeed see what appears to be spikes coming out from it. These are called diffraction spikes and appear because of the way the light enters your eye through what is essentially a small circular hole. Diffraction is the bending of light around the corner or edge of an obstruction, caused by the wave nature of light.
As for the twinkling, the scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation). Stars only twinkle when we observe them from the Earth's surface - stars would not appear to twinkle if we viewed them from outer space (or from a planet or moon that didn't have an atmosphere). This is because we are viewing them through thick layers of turbulent air in the Earth's atmosphere - as their light travels through the many layers of the atmosphere, the light of the star is bent (refracted) many times and in random directions as it moves through pockets of cold air or hot air. This random refraction results in the star 'winking'.
And did you know that stars closer to the horizon appear to twinkle more than stars that are overhead? This is because the light of stars near the horizon has to travel through more air than the light of stars overhead and so is subjected to more refraction.
Vega was actually the subject of Carl Sagan's science fiction novel Contact (1985), where a message is received on Earth from an extraterrestrial transmitter array orbiting Vega. You might remember the 1997 film of the novel, where the scientist who detected the signal is played by Jodie Foster and she is later transported to Vega via a wormhole. Foster 's character in the film, Ellie Arroway, worked for SETI - Search for Extraterrestrial Intelligence - a real-life scientific institution that conducts research on intelligent extraterrestrial life. Early last year, due to lack of funds, the institute had to shut down their Alien Telescope Array, which searches for radio signals from outer space. However, SETI later managed to raise $200,000 to continue the operation of the telescope through the end of the year. The funds were donated by over 2,000 private donors - including Jodie Foster.
The film also has one of the best astronomical movie quotes ever. When the young Ellie asks her father if he thinks there are people on other planets, he replies "I don't know .... But I guess I'd say if it is just us... seems like an awful waste of space."
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