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Alpha Centauri Q&A

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Q: How was the nearest star Alpha Centauri named that way?

A: Also called Rigel Kentaurus, the familiar 'Alpha Centauri' name comes from the bright star naming convention devised by Johann Bayer in 1603 in his atlas 'Uranometria'. He designated the brightest star in each constellation as 'Alpha' followed by the constellation name. It is, by the way, the third brightest star in the sky.

Q: How long does it take for light to get from Alpha Centauri to Earth?

A: It takes 4.3 years travelling at 300,000 kilometres per second or 186,287 miles per second. There are 31 million seconds in a year.

Q: I am going to Brazil. Where should I look for Alpha Centauri?

A: The declination of Alpha Centauri is -60.5 degrees. The latitude on the Earth for Brazil is about -15 degrees. This means that if you face North, polaris the north star will be 15 degrees below the horizon and never visible from your location, even though you will see the 'Big Dipper' rise and set each night. If you face south with, or course east to your LEFT and west to your RIGHT, you will see Alpha Centauri cross your meridian at an elevation of 45 degrees to the horizon.