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Rare exoplanet 41 EP

HD 2685 b

RA 7.3289° · Dec -76.3040° · exoplanet

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Score breakdown

· 6 badges
41 pts · Rare
Rare 50 pts → Epic
  • Lava world +14
  • Tidally locked +10
  • Confirmed exoplanet +5
  • Gas giant +4
  • Blasted by starlight +4
  • Found by TESS +4
Total score 41

9 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Lava world · +14
  • Tidally locked · +10
  • Blasted by starlight · +4
  • Found by TESS · +4

Trivia

What makes it special

  • Lava world. Its surface is almost certainly an ocean of molten rock, kept liquid by the star it hugs.

Hard to believe

  • It would float. It is less dense than water. Drop it in a big enough ocean and the whole world would bob on the surface.

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. Lighter than Neptune — a puffed-up ball of hydrogen and helium with no surface anywhere on it to stand on.

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 9.6 you'll want a small backyard telescope.
  • Southern sky only. So far south it never rises for most of the northern hemisphere. To see it you'd have to travel to Chile, South Africa or Australia.
  • Best time of year. It stands highest in the middle of the night around September — that's when to go looking.

Properties

density gcc
0.486
diameter km
205897.314
discovery facility
Transiting Exoplanet Survey Satellite (TESS)
discovery method
Transit
discovery year
2019
dist ly
642.0446
eccentricity
0.091
eq temp k
2061
host star teff
6801
inclination
89.252
insolation
1436.49
mag
9.595
mass earth
371.8611
name
HD 2685 b
orbital period days
4.1269
radius earth
16.141
semi major au
0.0568
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About HD 2685 b

HD 2685 b is a rare exoplanet. It lies about 642 light-years from Earth, shines at apparent magnitude 9.6, has an equilibrium temperature near 2,061 K and spans roughly 16.14 Earth radii.

Its surface is almost certainly an ocean of molten rock, kept liquid by the star it hugs.

How to see it

At apparent magnitude 9.6, a small backyard telescope will bring it into view.

Like any astronomical target, HD 2685 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 2685 b is a rare exoplanet

HD 2685 b scores 41 points on Spacedle's rarity scale, which places it in the rare tier. Another 9 points would lift it into a rarer tier.

That score comes from 6 science badges — Confirmed exoplanet, Gas giant, Lava world, Tidally locked, Blasted by starlight and Found by TESS — 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.