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Common exoplanet 20 EP

HD 28109 d

RA 65.2383° · Dec -68.1027° · exoplanet

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Score breakdown

· 4 badges
20 pts · Common
Common 22 pts → Uncommon
  • Multi-planet system +6
  • Confirmed exoplanet +5
  • Sub-Neptune +5
  • Found by TESS +4
Total score 20

2 more points to reach Uncommon.

Badges

  • Confirmed exoplanet · +5
  • Sub-Neptune · +5
  • Multi-planet system · +6
  • Found by TESS · +4

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. 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 3 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 9.4 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 November — that's when to go looking.

Could we get there?

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

Properties

density gcc
1.1
diameter km
39671.782
discovery facility
Transiting Exoplanet Survey Satellite (TESS)
discovery method
Transit
discovery year
2022
dist ly
455.3497
eccentricity
0.0054
eq temp k
561
host star teff
6189
inclination
89.77
insolation
17.3745
mag
9.42
mass earth
5.8
name
HD 28109 d
orbital period days
84.2899
radius earth
3.11
semi major au
0.411
spect
F8
sys num planets
3
sys num stars
1

About HD 28109 d

HD 28109 d is a common exoplanet. It lies about 455.3 light-years from Earth, shines at apparent magnitude 9.42, has spectral type F8 and has an equilibrium temperature near 561 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 9.42, a small backyard telescope will bring it into view.

Like any astronomical target, HD 28109 d 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 28109 d is a common exoplanet

HD 28109 d scores 20 points on Spacedle's rarity scale, which places it in the common tier. Another 2 points would lift it into a rarer tier.

That score comes from 4 science badges — Confirmed exoplanet, Sub-Neptune, Multi-planet system 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.