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Rare exoplanet 39 EP

K2-99 b

RA 208.7738° · Dec -5.4425° · exoplanet

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Score breakdown

· 6 badges
39 pts · Rare
Rare 50 pts → Epic
  • Hot Jupiter +10
  • Orbits a Sun-like star +8
  • Distant (over 1,000 light-years) +6
  • Multi-planet system +6
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 39

11 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Distant (over 1,000 light-years) · +6
  • Gas giant · +4
  • Hot Jupiter · +10
  • Multi-planet system · +6
  • Orbits a Sun-like star · +8

Trivia

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.
  • 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 11.1 you'll want a small backyard telescope.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • Best time of year. It stands highest in the middle of the night around April — that's when to go looking.

Properties

density gcc
0.9
diameter km
151563.0396
discovery facility
K2
discovery method
Transit
discovery year
2016
dist ly
1693.4965
eccentricity
0.22
eq temp k
1184
host star teff
6069
inclination
88.6
insolation
357
mag
11.149
mass earth
276.5107
name
K2-99 b
orbital period days
18.2478
radius earth
11.8815
semi major au
0.153
spect
G0 IV
sys num planets
2
sys num stars
1

About K2-99 b

K2-99 b is a rare exoplanet. It lies about 1,693.5 light-years from Earth, shines at apparent magnitude 11.15, has spectral type G0 IV and has an equilibrium temperature near 1,184 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 11.15, a small backyard telescope will bring it into view.

Like any astronomical target, K2-99 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 K2-99 b is a rare exoplanet

K2-99 b scores 39 points on Spacedle's rarity scale, which places it in the rare tier. Another 11 points would lift it into a rarer tier.

That score comes from 6 science badges — Confirmed exoplanet, Distant (over 1,000 light-years), Gas giant, Hot Jupiter, Multi-planet system 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.