Why does arcturus twinkle

Dim Pluto, invisible to the naked eye, sits in between the two gas giants. Mars rises around 8 p. Mars is very bright — brighter than Jupiter — and is worth staying up late to observe. Mars and the Moon are very close to each other on the night of Oct. Have a question about astronomy or space science? Send an email to dan starpointestudio. Please log in, or sign up for a new account and purchase a subscription to read or post comments.

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Including the sun, Arcturus is the fifth brightest star in the sky. Since it sets just after 8pm, you will have to be out PDQ after sundown to catch a glimpse before it disappears. Look for a rapidly twinkling orange star very close to the northwestern horizon. En-route to your eye, starlight passes through atmospheric clumps of different temperature, density and humidity. Each blob behaves like a lens, creating an image of the star. As the atmosphere moves, the number and position of these individual images changes.

These multiple images make starlight appear to scintillate when viewed from the ground. Scientists call this atmospheric refraction. When stars are near the horizon, we observe them through a thicker atmospheric column, which means they tend to twinkle more when they are low.

Arcturus usually looks orange-red to the unaided eye — do let me know what colours you see if you spot it this week. Our second star is Vega in the constellation Lyra.

Once this is accounted for, Arcturus actually releases times more heat than Earth's sun. Arcturus has an apparent magnitude of The brighter the star, the lower its apparent and absolute magnitudes. The star is in the latter stages of its life.

Considered a red giant, Arcturus has stopped fusing hydrogen in its core, as the sun does, and astronomers believe it is now starting to fuse heavier elements such as carbon. Once Arcturus exhausts its helium supply, its outer layers will likely bleed off, leaving behind a white dwarf remnant. No planets have been found surrounding this star, although science fiction has explored that subject.

The book's protagonist travels to Tormance, a fictional planet that orbits Arcturus. Arcturus — either the star or a fictional planet with the same name — has also appeared in many other science fiction series, including Isaac Asimov's "Foundation" book series, the "Doctor Who" and "Star Trek" television series, and the movie "Aliens.

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