About WASP-39 b
WASP-39 b is an uncommon exoplanet. It lies about 697.9 light-years from Earth, has an equilibrium temperature near 1,166 K, spans roughly 14.34 Earth radii and weighs about 89.31 Earth masses.
So low-density it would float on water.
Uncommon exoplanet 31 EP
WASP-39 b
RA 217.3266° · Dec -3.4445° · exoplanet
Score breakdown
· 4 badgesUncommon 33 pts → Rare
- Puffy low-density world +12
- Hot Jupiter +10
- Confirmed exoplanet +5
- Gas giant +4
Total score 31
2 more points to reach Rare.
Badges
- Confirmed exoplanet · +5
- Gas giant · +4
- Hot Jupiter · +10
- Puffy low-density world · +12
Trivia
What makes it special
- Cotton-candy planet. So low-density it would float on water.
Could we get there?
- Verdict. Hopelessly far for any craft humanity can build today.
Getting there
- Aboard Voyager 1. ≈ 12.3 million years at Voyager 1's speed (17 km/s).
- Fastest probe ever. ≈ 1.1 million years even at the Parker Solar Probe's 192 km/s.
- At 10% light speed. ≈ 6979 years in a starship at a tenth of light speed.
- Distance. 698 light-years from Earth.
Look-back time
- Look-back time. The light you'd see left around the year 1328.
Saying hello
- Say hello. A radio message and its reply would take 1396 years round-trip.
Standing on it
- A year here. A full year lasts just 4.1 Earth days.
By the numbers
- Size. About 14.3× the width of Earth.
- Volume. About 2947 Earths could fit inside it.
- Mass. Roughly 89.3× Earth's mass — about 0.3 Jupiters.
- Your weight. You'd weigh about 0.4× your Earth weight standing here.
- Density. Less dense than water — drop it in a big enough ocean and it would float.
- Temperature. Around 893°C — hotter than a self-cleaning oven.
How we found it
- Discovery. Found by SuperWASP using the transit method.
Properties
- density gcc
- 0.167
- discovery facility
- SuperWASP
- discovery method
- Transit
- dist ly
- 697.9151
- eccentricity
- 0
- eq temp k
- 1166
- insolation
- 316.269
- mass earth
- 89.3102
- name
- WASP-39 b
- orbital period days
- 4.0553
- radius earth
- 14.3363
- sys num planets
- 1
How to see it
Like any astronomical target, WASP-39 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-39 b is an uncommon exoplanet
WASP-39 b scores 31 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 2 points would lift it into a rarer tier.
That score comes from 4 science badges — Confirmed exoplanet, Gas giant, Hot Jupiter and Puffy low-density world — 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.