Gliese 625 GJ 667 C TRAPPIST-121 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40d
bc
bb cfegbcdefghWWW.ASTRONOMY.COM 51From a planet circling
Proxima Centauri to several
around TRAPPIST-1,
life-friendly worlds might
be closer than you think.
BY JOHN WENZ
By 1995, astronomers had
detected only one planet around
a Sun-like star.
Today, we have discovered
more than 4,000 extrasolar plan-
ets. Of those, only about 50 are
considered habitable by the most
optimistic projections, meaning
they could have liquid water and a
rocky surface. And only about 20
likely have Earth-like temperatures.So, if we decided to send off
a probe to chart other habitable
planets — or somehow even
visit them ourselves — where
would we go? Here are a few of
the nearest places, known as of
October 2019.John Wenz is digital producer at
Knowable Magazine and a former
associate editor of Astronomy.Gliese 625
GJ 667 C
TRAPPIST-1
Distance: 14 light-years
Star type: Red dwarf
Habitable planets: 1 (c)
Discovered: 2015
Mass: 3.41 Earths
Orbit: 17.9 d ay sDistance: 21 light-years
Star type: Red dwarf
Habitable planets: 1 (b)
Discovered: 2017
Mass: 2.82 Earths
Orbit: 14.6 daysDistance: 24 light-years
Star type: : Red dwarf
Habitable planets: 1 (c)
Discovered: 2011
Mass: 3.8 Earths
Orbit: 28.1 daysDistance: 17 l i g ht- ye a r s
Star type: Red dwarf
Habitable planets: 1 (b)
Discovered: 2017
Mass: 2.02 Earths
Orbit: 5.4 daysDistance: 39 light-years
Star type: : Red dwarf
Habitable planets:
2 to 6 (c, d, e, f, g, h)
Discovered: 2016, 2017
Mass: 0.35 to 1.38 Earths
Orbit: 2.4 to 18.8 daysASTRONOMY:^ ROE
N^ KELLY