Cygnus
Constellation · The Swan
Cygnus is a swan flying along the Milky Way. Its brightest star, Deneb, together with Vega and Altair, forms the Summer Triangle. The Kepler space telescope stared at a patch of sky near Cygnus to discover thousands of planets around other stars.
- The Northern CrossAlso called
- DenebBrightest star
- The Summer TrianglePart of
Take a closer look
Deneb, the far-off beacon
Vega and Altair, the other two stars of the Summer Triangle, are both within about 25 light-years of us. Deneb is well over a thousand light-years away, yet it still shines brightly in our sky. To manage that, it must shine tens of thousands of times more strongly than the Sun.
The first star measured
In 1838 Friedrich Bessel measured the distance to a faint star in Cygnus called 61 Cygni – the first star other than the Sun ever measured. He tracked how it shifts slightly as Earth moves around the Sun. It turned out to be about 11 light-years away.
A continent in the sky
Near Deneb glows the North America Nebula, a cloud of gas shaped remarkably like the continent, with dark dust forming its “Gulf of Mexico”. Running through Cygnus is the Great Rift, a lane of dark dust that seems to split the Milky Way in two.
How we found out
- Ancient Greece
In one story the swan is the god Zeus in disguise.
- 1964
Cygnus X-1 is discovered – later the first object widely accepted to be a black hole.
- 2009–2013
NASA’s Kepler telescope watches about 150,000 stars in Cygnus and Lyra and finds thousands of exoplanets.
How can you find a planet around another star if you can’t see it?
Kepler looked for tiny dips in a star’s brightness when a planet passed in front of it – like a moth flying past a distant streetlight.
See it yourself
High overhead on northern summer evenings. Look for a long cross shape along the Milky Way.
From the encyclopedia
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