← Back to dex
Epic exoplanet 67 EP

WASP-78 b

RA 63.7563° · Dec -22.1164° · exoplanet

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

Computing the sky for your location…

Score breakdown

· 7 badges
67 pts · Epic
Epic 78 pts → Anomaly
  • Ultra-hot Jupiter +26
  • Puffy low-density world +12
  • Tidally locked +10
  • Distant (over 1,000 light-years) +6
  • Confirmed exoplanet +5
  • Gas giant +4
  • Blasted by starlight +4
Total score 67

11 more points to reach Anomaly.

Badges

  • Confirmed exoplanet · +5
  • Distant (over 1,000 light-years) · +6
  • Gas giant · +4
  • Ultra-hot Jupiter · +26
  • Tidally locked · +10
  • Puffy low-density world · +12
  • Blasted by starlight · +4

Trivia

What makes it special

  • Ultra-hot Jupiter. So hot that iron vaporises on the dayside, blows around to the night side and rains back down as molten metal.

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.

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 12 you'll want a small backyard telescope.
  • 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 November — that's when to go looking.

Properties

density gcc
0.131
diameter km
275959.5944
discovery facility
SuperWASP
discovery method
Transit
discovery year
2012
dist ly
2460.0577
eccentricity
0
eq temp k
2469.7
host star teff
6100
inclination
83.2
insolation
4812.6238
mag
11.965
mass earth
352.7913
name
WASP-78 b
orbital period days
2.1752
radius earth
21.6334
semi major au
0.0349
sys num planets
1
sys num stars
1
tidally locked
yes
tidally locked inferred
yes

About WASP-78 b

WASP-78 b is an epic exoplanet. It lies about 2,460.1 light-years from Earth, shines at apparent magnitude 11.96, has an equilibrium temperature near 2,470 K and spans roughly 21.63 Earth radii.

So hot that iron vaporises on the dayside, blows around to the night side and rains back down as molten metal.

How to see it

At apparent magnitude 11.96, a small backyard telescope will bring it into view.

Like any astronomical target, WASP-78 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 WASP-78 b is an epic exoplanet

WASP-78 b scores 67 points on Spacedle's rarity scale, which places it in the epic tier. Another 11 points would lift it into a rarer tier.

That score comes from 7 science badges — Confirmed exoplanet, Distant (over 1,000 light-years), Gas giant, Ultra-hot Jupiter, Tidally locked, Puffy low-density world and Blasted by starlight — 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.