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Uncommon exoplanet 27 EP

KMT-2021-BLG-0909L b

RA 265.6202° · Dec -27.6391° · exoplanet

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Score breakdown

· 4 badges
27 pts · Uncommon
Uncommon 34 pts → Rare
  • Found by microlensing +12
  • Distant (over 1,000 light-years) +6
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 27

7 more points to reach Rare.

Badges

  • Confirmed exoplanet · +5
  • Distant (over 1,000 light-years) · +6
  • Gas giant · +4
  • Found by microlensing · +12

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

  • 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

  • Southern sky. It rides the southern half of the sky — an easier target the further south you are.
  • Best time of year. It stands highest in the middle of the night around June — that's when to go looking.

Could we get there?

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

Getting there

  • Aboard Voyager 1. ≈ 371.4 million years at Voyager 1's speed (17 km/s).
  • Fastest probe ever. ≈ 33 million years even at the Parker Solar Probe's 192 km/s.

Properties

density gcc
0.856
diameter km
174759.94
discovery facility
KMTNet
discovery method
Microlensing
discovery year
2023
dist ly
21134.9088
mass earth
400.4638
name
KMT-2021-BLG-0909L b
radius earth
13.7
semi major au
1.75
sys num planets
1
sys num stars
1

Nearby objects

About KMT-2021-BLG-0909L b

KMT-2021-BLG-0909L b is an uncommon exoplanet. It lies about 21,134.9 light-years from Earth, spans roughly 13.7 Earth radii, weighs about 400.46 Earth masses and belongs to a system of 1 known planets.

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

How to see it

Like any astronomical target, KMT-2021-BLG-0909L 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 KMT-2021-BLG-0909L b is an uncommon exoplanet

KMT-2021-BLG-0909L b scores 27 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 7 points 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 Found by microlensing — 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.