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Common exoplanet 15 EP

HAT-P-17 b

RA 324.5360° · Dec 30.4882° · exoplanet

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Score breakdown

· 3 badges
15 pts · Common
Common 22 pts → Uncommon
  • Multi-planet system +6
  • Confirmed exoplanet +5
  • Gas giant +4
Total score 15

7 more points to reach Uncommon.

Badges

  • Confirmed exoplanet · +5
  • Gas giant · +4
  • Multi-planet system · +6

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 10.4 you'll want a small backyard telescope.
  • 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.

Properties

density gcc
0.44
diameter km
150133.4581
discovery facility
HATNet
discovery method
Transit
discovery year
2012
dist ly
301.313
eccentricity
0.35
eq temp k
800
host star teff
5246
inclination
89.2
insolation
110.512
mag
10.375
mass earth
184.3414
name
HAT-P-17 b
orbital period days
10.3385
radius earth
11.7695
semi major au
0.0892
spect
K
sys num planets
2
sys num stars
1

About HAT-P-17 b

HAT-P-17 b is a common exoplanet. It lies about 301.3 light-years from Earth, shines at apparent magnitude 10.38, has spectral type K and has an equilibrium temperature near 800 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 10.38, a small backyard telescope will bring it into view.

Like any astronomical target, HAT-P-17 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 HAT-P-17 b is a common exoplanet

HAT-P-17 b scores 15 points on Spacedle's rarity scale, which places it in the common tier. Another 7 points would lift it into a rarer tier.

That score comes from 3 science badges — Confirmed exoplanet, Gas giant and Multi-planet system — 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.