← Back to dex
Rare exoplanet 37 EP

AT2021ueyL b

RA 324.5450° · Dec 26.4666° · exoplanet

Loading sky survey…
🌌 View in 3D star map
Tonight’s visibility

Computing the sky for your location…

Score breakdown

· 5 badges
37 pts · Rare
Rare 50 pts → Epic
  • Found by microlensing +12
  • Long-period world +10
  • Distant (over 1,000 light-years) +6
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 37

13 more points to reach Epic.

Badges

  • Confirmed exoplanet · +5
  • Distant (over 1,000 light-years) · +6
  • Gas giant · +4
  • Long-period world · +10
  • 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

  • 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 August — 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. ≈ 59.6 million years at Voyager 1's speed (17 km/s).
  • Fastest probe ever. ≈ 5.3 million years even at the Parker Solar Probe's 192 km/s.

Properties

density gcc
0.93
diameter km
173484.32
discovery facility
Multiple Observatories
discovery method
Microlensing
discovery year
2025
dist ly
3392.0224
host star teff
3680
mass earth
425.8901
name
AT2021ueyL b
orbital period days
4168.69
radius earth
13.6
semi major au
4.01
spect
M V
sys num planets
1
sys num stars
1

Nearby objects

About AT2021ueyL b

AT2021ueyL b is a rare exoplanet. It lies about 3,392 light-years from Earth, has spectral type M V, spans roughly 13.6 Earth radii and weighs about 425.89 Earth masses.

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, AT2021ueyL 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 AT2021ueyL b is a rare exoplanet

AT2021ueyL b scores 37 points on Spacedle's rarity scale, which places it in the rare tier. Another 13 points would lift it into a rarer tier.

That score comes from 5 science badges — Confirmed exoplanet, Distant (over 1,000 light-years), Gas giant, Long-period world 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.