K2-33 b
K2-33 b is a Neptune-like planet orbiting the M3.3 star K2-33 in the constellation Scorpius. It lies about 454 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is K2-33 b?
K2-33 b has a radius of 5.04 times that of Earth. Its mass is 1,176 times that of Earth.
Is K2-33 b in the Habitable Zone?
The position of K2-33 b relative to the habitable zone of K2-33 cannot be precisely determined from the available orbital data.
Habitable zone of K2-33: 0.317–0.820 AU (conservative: 0.401–0.777 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Orbit and Year Length
A year on K2-33 b — one full orbit around K2-33 — lasts 5.42 Earth days, shorter than Mercury's 88-day year.
How Was K2-33 b Discovered?
K2-33 b was discovered in 2016 using the transit method, with observations from K2.
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is K2-33 b?
K2-33 b is 454.2 light-years (139.3 parsecs) from Earth. Light arriving here tonight left the planet around the year 1572. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 7,993,920 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. K2-33 b scores 0.16, ranking #4,132 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-33
K2-33
- Spectral type
- M3.3
- Surface temperature
- 3,540 K (Sun: 5,772 K)
- Mass
- 0.56 M☉
- Radius
- 1.05 R☉
- Luminosity
- 0.1500 L☉
- Age
- 0.0 billion years (Sun: 4.6)
Planetary System
K2-33 b is the only planet known to orbit K2-33 so far.
K2-33 b — Complete Data
| Radius | 5.040 Earth radii (0.450 Jupiter radii) |
|---|---|
| Mass | 1,175.97 Earth masses (3.700 Jupiter masses) |
| Orbital period | 5.42 days |
| Earth Similarity Index | 0.16 |
| Distance from Earth | 454.2 light-years (139.3 parsecs) |
| Constellation | Scorpius |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2016-07-06. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-33 b
Is K2-33 b habitable?
K2-33 b is not known to orbit within the habitable zone of K2-33, and as a Neptune-like planet it is an unlikely candidate for life as we know it.
How far away is K2-33 b?
K2-33 b is about 454 light-years from Earth in the constellation Scorpius. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 7,993,920 years to get there.
How big is K2-33 b compared to Earth?
K2-33 b has 5.04 times the radius of Earth and about 1,176 times its mass.
How long is a year on K2-33 b?
One orbit around K2-33 takes 5.4 Earth days — short enough that 67 of its years would fit into one Earth year.
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