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Common exoplanet 21 EP

BD+20 2457 c

RA 154.1868° · Dec 19.8913° · exoplanet

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Score breakdown

· 4 badges
21 pts · Common
Common 22 pts → Uncommon
  • Distant (over 1,000 light-years) +6
  • Multi-planet system +6
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 21

1 more point to reach Uncommon.

Badges

  • Confirmed exoplanet · +5
  • Distant (over 1,000 light-years) · +6
  • Gas giant · +4
  • Multi-planet system · +6

Trivia

Hard to believe

  • Denser than iron. It is packed tighter than solid iron — whatever it is made of, it is not ordinary rock.

What it actually is

  • What it is made of. Denser than Earth — a solid world of rock and iron, with no meaningful atmosphere to speak of by mass.
  • Crowded system. One of at least 2 planets orbiting its star.

Sense of scale

  • In perspective. Far away by human standards, yet still a local address inside the Milky Way's spiral arms.

Find it in the sky

  • How to spot it. At magnitude 9.7 you'll want a small backyard telescope.
  • Northern sky. It rides the northern half of the sky — an easier target the further north you are.
  • Best time of year. It stands highest in the middle of the night around February — that's when to go looking.

Could we get there?

  • Verdict. Impossible with our current technology — and the next millennium of it.

Properties

density gcc
11.4
diameter km
158176.88
discovery facility
McDonald Observatory
discovery method
Radial Velocity
discovery year
2009
dist ly
5021.8565
eccentricity
0.18
eq temp k
984.96
host star teff
4137
insolation
366.1069
mag
9.743
mass earth
3963.17
name
BD+20 2457 c
orbital period days
621.99
radius earth
12.4
semi major au
2.01
spect
K2 II
sys num planets
2
sys num stars
1

About BD+20 2457 c

BD+20 2457 c is a common exoplanet. It lies about 5,021.9 light-years from Earth, shines at apparent magnitude 9.74, has spectral type K2 II and has an equilibrium temperature near 985 K.

Denser than Earth — a solid world of rock and iron, with no meaningful atmosphere to speak of by mass.

How to see it

At apparent magnitude 9.74, a small backyard telescope will bring it into view.

Like any astronomical target, BD+20 2457 c is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. The visibility panel above works out tonight's viewing window for your saved location.

Why BD+20 2457 c is a common exoplanet

BD+20 2457 c scores 21 points on Spacedle's rarity scale, which places it in the common tier. Another 1 point would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, Distant (over 1,000 light-years), Gas giant and Multi-planet system — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.