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Stars · Sun-like

Tau Ceti: the nearest single star like the Sun

Tau Ceti, a pale yellow-white Sun-like star, drawn in Exo-View

Tau Ceti is 11.9 light-years away in the constellation Cetus, and it is the nearest single star that is anything like the Sun: a little smaller, a little cooler, and just bright enough to see with the naked eye from a dark site. It has a belt of debris round it and signs of several small planets, which is why people have wondered about it for more than sixty years.

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Distance
11.9 light-years
Kind
Yellow dwarf, spectral type G8, a close cousin of the Sun
Size
0.79 times the Sun's width
Surface temperature
About 5,340 K, against the Sun's 5,800 K
Brightness
About half the Sun's light; magnitude 3.5, visible to the naked eye from a dark site
Spin
Once in about 34 days
Planets
Four candidates, g, h, e and f, with orbits of 20, 49, 163 and 636 days

Why it matters

Most of the stars near the Sun are red dwarfs. Tau Ceti is one of only a few close, single stars with a mass and temperature near ours, so it is a natural place to look for a planetary system like ours. In 1960 Frank Drake pointed a radio telescope at it, with Epsilon Eridani, in Project Ozma, the first search for a signal from another civilisation, and heard nothing.

Its planets, and a word of caution

In 2017 astronomers combining thousands of measurements of the star's wobble reported four planets, each a few times the Earth's mass. The signals are very small, about the size of the star's own noise, so the four are treated as candidates rather than certain. The two outer ones, e and f, would lie at the warm and cold edges of the habitable zone. The star is also ringed by a disc of dust and comets about ten times denser than our own Kuiper Belt, so any planet there would be pelted by far more impacts than the Earth.

In Exo-View

The key below flies from the Sun to Tau Ceti. The four candidates are drawn in their orbits, as an illustration made from their figures: the surfaces are not photographs, and the plates say so.

Fly to Tau CetiSee the Milky Way

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