MASCARA-4 b
MASCARA-4 b is a hot Jupiter orbiting MASCARA-4 in the constellation Carina. It lies about 557 light-years from Earth and was discovered in 2020 using the transit method.
How Big Is MASCARA-4 b?
MASCARA-4 b has a radius of 16.98 times that of Earth, or 1.52 times the radius of Jupiter. Its mass is 532 times that of Earth, giving it a density of 0.48 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is MASCARA-4 b in the Habitable Zone?
The position of MASCARA-4 b relative to the habitable zone of MASCARA-4 cannot be precisely determined from the available orbital data.
Temperature on MASCARA-4 b
The equilibrium temperature of MASCARA-4 b is about 2,250 K (1,977 °C) — hot enough to melt many metals. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C.
Orbit and Year Length
A year on MASCARA-4 b — one full orbit around MASCARA-4 — lasts 2.82 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.047 AU — closer to its star than Mercury is to the Sun.
How Was MASCARA-4 b Discovered?
MASCARA-4 b was discovered in 2020 using the transit method, with observations from Multiple Observatories.
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 MASCARA-4 b?
MASCARA-4 b is 556.7 light-years (170.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1470. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 9,797,920 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. MASCARA-4 b scores 0.05, ranking #5,246 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: MASCARA-4
MASCARA-4 b belongs to a system of 2 stars; it orbits MASCARA-4.
MASCARA-4
- Surface temperature
- 7,800 K (Sun: 5,772 K)
- Mass
- 1.75 M☉
- Radius
- 1.79 R☉
Planetary System
MASCARA-4 b is the only planet known to orbit MASCARA-4 so far.
MASCARA-4 b — Complete Data
| Radius | 16.982 Earth radii (1.515 Jupiter radii) |
|---|---|
| Mass | 532.36 Earth masses (1.675 Jupiter masses) |
| Density | 0.48 g/cm³ (Earth: 5.51) |
| Orbital period | 2.82 days |
| Orbital distance | 0.047 AU |
| Equilibrium temperature | 2,250 K (1,977 °C) |
| Earth Similarity Index | 0.05 |
| Distance from Earth | 556.7 light-years (170.7 parsecs) |
| Constellation | Carina |
| Discovery method | Transit |
| Discovery facility | Multiple Observatories |
| Discovery year | 2020 |
Data: NASA Exoplanet Archive, last updated 2025-06-11. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About MASCARA-4 b
Is MASCARA-4 b habitable?
MASCARA-4 b is not known to orbit within the habitable zone of MASCARA-4, and as a hot Jupiter it is an unlikely candidate for life as we know it.
How far away is MASCARA-4 b?
MASCARA-4 b is about 557 light-years from Earth in the constellation Carina. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 9,797,920 years to get there.
How big is MASCARA-4 b compared to Earth?
MASCARA-4 b has 16.98 times the radius of Earth and about 532 times its mass.
How long is a year on MASCARA-4 b?
One orbit around MASCARA-4 takes 2.8 Earth days — short enough that 129 of its years would fit into one Earth year.
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