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Uncommon exoplanet 26 EP

HD 17156 b

RA 42.4366° · Dec 71.7531° · exoplanet

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Score breakdown

· 4 badges
26 pts · Uncommon
Uncommon 34 pts → Rare
  • Eccentric orbit +9
  • Orbits a Sun-like star +8
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 26

8 more points to reach Rare.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Eccentric orbit · +9
  • Orbits a Sun-like star · +8

Trivia

What it actually is

  • Hugging its star. It orbits closer to its star than Mercury does to the Sun, completing a lap in less time than Mercury takes.
  • What it is made of. Its density says rock, though lighter than Earth's mix: probably less iron, or a thick shell of water and ice over the top.

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 8.2 it is just past naked-eye reach — ordinary binoculars will pull it in.
  • Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
  • Best time of year. It stands highest in the middle of the night around November — that's when to go looking.

Could we get there?

  • Verdict. Hopelessly far for any craft humanity can build today.

Getting there

  • Aboard Voyager 1. ≈ 4.5 million years at Voyager 1's speed (17 km/s).

Properties

density gcc
3.08
diameter km
156424.4956
discovery facility
Subaru Telescope
discovery method
Radial Velocity
discovery year
2007
dist ly
254.6832
eccentricity
0.6772
eq temp k
888
host star teff
6046
inclination
86.51
insolation
68.8
mag
8.17
mass earth
1036.1206
name
HD 17156 b
orbital period days
21.2164
radius earth
12.2626
semi major au
0.1632
spect
G5
sys num planets
1
sys num stars
1

About HD 17156 b

HD 17156 b is an uncommon exoplanet. It lies about 254.7 light-years from Earth, shines at apparent magnitude 8.17, has spectral type G5 and has an equilibrium temperature near 888 K.

It orbits closer to its star than Mercury does to the Sun, completing a lap in less time than Mercury takes.

How to see it

At apparent magnitude 8.17, it is an easy target for binoculars.

Like any astronomical target, HD 17156 b 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 HD 17156 b is an uncommon exoplanet

HD 17156 b scores 26 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 8 points would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, Gas giant, Eccentric orbit and Orbits a Sun-like star — 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.