Astronomy Questions & Answers

How can binary stars orbit each other so fast?

In a News Note (S&T: November 2004, page 16) you described WR 20a, a binary star in Carina with components of 83 and 82 solar masses and an orbital period of 3.686 days. How can two huge balls of gas move so fast? Grab any introductory astronomy textbook and turn…

Alpha, Beta, and Proxima Centauri

Astronomy Questions & Answers

What date were the two principal stars of the Alpha Centauri system last known to be closest to each other?

On what terrestrial date were the two principal stars of the Alpha Centauri system last known to be closest to each other in space? According to the orbit recently published by Belgian astronomer Dimitri Pourbaix, α1 and α2 Centauri were closest in space (at periastron) in early August 1955, and…

Astronomy Questions & Answers

If you combine the magnitudes of all visible stars, how bright a star will you come up with?

Just wondering. . . . If you combine the magnitudes of all visible stars (down to 6th magnitude), how bright a star will you come up with? About 9,000 stars are brighter than magnitude 6.5, the traditional criterion for naked-eye visibility. Their combined magnitude is almost exactly –5, which is…

Science-based Q&A

If you lived on Saturn, would its rings be visible from the equator or the poles?

If I lived on Saturn, would its rings be visible from the equator or the poles? Above the cloudtops and neglecting refraction, geometry dictates that you’d see nothing from the poles. As you moved toward the equator, the bright A ring would start coming into view at latitude 66° (roughly…

Astronomy Questions & Answers

How can we find the Sun's place among the constellations?

How can I find out how our Sun would look among the constellations, as seen from a nearby star? What made me curious was a painting by space artist David Hardy that pictured the Sun as an extra star in Cassiopeia. Fancy planetarium projectors produce such scenes, but you can…

Hobby-based Q&A

Were stars artistically depicted with diffraction spikes before the invention of the Newtonian reflector?

Were stars artistically depicted with diffraction spikes before the invention of the Newtonian reflector? If so, why? Stars were being drawn with points or spikes long before Isaac Newton announced his reflecting telescope in 1671. Just look at early works of art, flags, ancient coins, and the charts of the…

Light curves by class

Science-based Q&A

Why Are There No Green Stars?

There are red stars, orange stars, yellow stars, and blue stars. Why no green stars?

Twisting the night away

Astronomy Questions & Answers

How do astronomers accurately determine wobbles in a star's motion?

The discovery of planets around other stars is based on wobbles in the stars' motions. Don't you have to measure from a stationary point in space to accurately determine this/ Isn't there an added wobble because Earth rotates on its axis and travels around the Sun? Yes, Earth's rotation and…

Hobby-based Q&A

How do you pronounce “Vega” and “Canis Major”?

How do you pronounce “Vega”? “Canis Major”? In 1941 the American Astronomical Society formed a committee of Samuel G. Barton, George A. Davis Jr., and Daniel J. McHugh to consult with astronomers, educators, Arabic scholars, and planetarium lecturers and come up with a list of preferred pronunciations for common star…

Stand-out star on the rise in December

Science-based Q&A

Why are the stars so far away?

Why are the stars so far away? That question has a real answer: Because if the stars were much closer, Earth wouldn’t exist, and we wouldn’t be here to ask.

The center of the stellar merry-go-round

Hobby-based Q&A

What's the distance to Polaris?

I have three astronomy programs on my computer that give three different distances for Polaris. I just obtained a fourth program, and it says the distance is unknown. What’s the problem? Those new to astronomy expect the distances of bright stars to be very accurately known, but many still aren’t.…

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