About XO-3 b
XO-3 b is a rare exoplanet. It lies about 694.9 light-years from Earth, has an equilibrium temperature near 1,890 K, spans roughly 14.8 Earth radii and weighs about 4,217.58 Earth masses.
Its surface is likely an ocean of molten rock.
Rare exoplanet 41 EP
XO-3 b
RA 65.4696° · Dec 57.8172° · exoplanet
Score breakdown
· 5 badgesRare 46 pts → Epic
- Lava world +14
- Hot Jupiter +10
- Blasted by starlight +8
- Confirmed exoplanet +5
- Gas giant +4
Total score 41
5 more points to reach Epic.
Badges
- Confirmed exoplanet · +5
- Gas giant · +4
- Hot Jupiter · +10
- Lava world · +14
- Blasted by starlight · +8
Trivia
What makes it special
- Lava world. Its surface is likely an ocean of molten rock.
Could we get there?
- Verdict. Hopelessly far for any craft humanity can build today.
Getting there
- Aboard Voyager 1. ≈ 12.2 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. ≈ 6949 years in a starship at a tenth of light speed.
- Distance. 695 light-years from Earth.
Look-back time
- Look-back time. The light you'd see left around the year 1331.
Saying hello
- Say hello. A radio message and its reply would take 1390 years round-trip.
Standing on it
- A year here. A full year lasts just 3.2 Earth days.
By the numbers
- Size. About 14.8× the width of Earth.
- Volume. About 3239 Earths could fit inside it.
- Mass. Roughly 4218× Earth's mass — about 13.3 Jupiters.
- Your weight. You'd weigh about 19.3× your Earth weight standing here.
- Temperature. Around 1617°C — hotter than a self-cleaning oven.
How we found it
- Discovery. Found by XO using the transit method.
Properties
- density gcc
- 7.16
- discovery facility
- XO
- discovery method
- Transit
- dist ly
- 694.8851
- eccentricity
- 0.2791
- eq temp k
- 1890
- insolation
- 1161.72
- mass earth
- 4217.583
- name
- XO-3 b
- orbital period days
- 3.1915
- radius earth
- 14.7959
- sys num planets
- 1
How to see it
Like any astronomical target, XO-3 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 XO-3 b is a rare exoplanet
XO-3 b scores 41 points on Spacedle's rarity scale, which places it in the rare tier. Another 5 points would lift it into a rarer tier.
That score comes from 5 science badges — Confirmed exoplanet, Gas giant, Hot Jupiter, Lava 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.