Can TRAPPIST-1 be seen in the night sky?

TRAPPIST-1, with its seven planets, is relatively close to Earth. But can it be seen in the night sky?

TRAPPIST-1 and its newly discovered seven orbiting planets are a relatively close 39 light years away, so can the star be seen in the night sky?

Not without a powerful telescope.

The star can be found within the constellation Aquarius, but as a red dwarf star, it is relatively dim in the portion of the light spectrum visible to human eyes. 

That’s why scientists needed NASA’s infrared Spitzer Space Telescope to study it and reveal the Earth-like planets around it.

TRAPPIST-1's apparent magnitude -- the term for how bright it looks as viewed from Earth -- is 18.8, a level that requires a large telescope to see.

In comparison, Saturn, which is about the seventh-brightest object in Earth's sky, has an apparent magnitude of 1. Binoculars or a telescope are required to see anything of magnitude 5 or greater -- the higher the magnitude, the dimmer the object.

Other stars at similar distances as TRAPPIST-1 can be more easily seen because they are bigger and brighter varieties of stars.

Arcturus and Denebola, two of the bright stars of the "summer triangle," are both only a few light years closer than TRAPPIST-1, but have apparent magnitudes of about 2 and 0.74, respectively.

Pollux, one of the twin stars of the constellation Gemini, is also only a few light years closer than TRAPPIST-1, but has an apparent magnitude of 1.14.

The brightest stars in the sky illustrate that distance is not the only factor in how stars appear.

Sirius, the brightest star in the night sky, is practically next door at 8.6 light years away. But Canopus, the second-brightest, is more than 300 light years away.

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