A screenshot from SpaceEngine showing the planetary system TOI-1136. The system has six planets, and in this image they are all aligned.

Author: Dr. Megan Tannock

Today’s update includes several smaller updates to several SpaceEngine features. The first is a major exoplanet catalog expansion. We have added 336 new exoplanets, 214 new exoplanet host stars, eight new brown dwarfs/stellar binaries, and added 30 missing stellar binary 'B' components of exoplanet-hosting systems. Additionally, we have updated asteroid binaries and Saturn’s moons, and made many other catalog corrections, including removing duplicate objects and correcting naming inconsistencies.

We have also added some minor bug fixes for the Climate Model. These include fixing a bug where temperatures were constant across the surfaces of planets with extremely thin atmospheres, and fixing a bug where secondary stars were being ignored in some planet surface temperature calculations.

As of November 30, 2023 the NASA Exoplanet Archive reports a whopping 5,539 confirmed exoplanets and brown dwarf companions from researchers all over the world. The number of confirmed exoplanets surpassed 5,500 in August 2023. To celebrate this numeric milestone, and the SpaceEngine catalogs update, we are highlighting five exciting exoplanet discoveries and updates from 2023 you can visit in-game today!

A screenshot from SpaceEngine showing the planetary system TOI-1136. The system has six planets, and in this image they are all aligned.

This spectacular alignment of the resonant TOI-1136 system was found using the SpaceEngine Event Finder, released earlier this year. In-game, this alignment takes place on Dec 31 of the year 1422.

Extraordinary exoplanet discoveries kicked off in January with the discovery of a young, six-planet system called TOI-1136. The planets of this well-organized system have extremely well-aligned inclinations, all orbiting within 1.1 degrees of the same plane! The host star’s rotation is also aligned with these orbital planes. Additionally, the TOI-1136 system is deeply resonant, meaning the orbital periods of all of the planets are correlated, likely as a result of being formed in an isolated disk with no other stars nearby. Resonance is due to the gravitational influence of the planets on each other. We see examples of resonance in our own solar system, such as the 3:2 resonance between Neptune and Pluto, meaning for every three orbits Neptune makes of the Sun, Pluto only completes two!

A SpaceEngine screenshot showing the planet TOI-5205 b next to its host star. The star is only about 4 times larger in diameter than the planet.

This diameter-comparison between TOI-5205 b and its host star was made using the “Solar System Chart” mode in-game. Note the sizes of the star and planet are to scale, but, in this mode, the distance between them is not.

In February, an unexpected discovery was made: a Jupiter-sized gas giant planet named TOI-5205 b, orbiting a small, mid-M type dwarf star. Typically, smaller stars host smaller, rocky planets. But the gas giant TOI-5205 b defies this pattern, with a radius just 3.7 times smaller than its host star. The existence of TOI-5205 b goes against astronomers’ theories of how gas giant planets form; current models require large amounts of rocky material and gas to be available during the star’s youth to form gas giant planets similar to Jupiter. Small, M-type stars are unlikely to have sufficient material around them, by a factor of around five times less material available than needed! TOI-5205 b has left astronomers reconsidering what they know about gas giants and how they form.

A screenshot from SpaceEngine showing the planet LTT 1445 A c with two of the other stars in the system in the background.

Part of LTT 1445 A c is partly shadowed, with the faint M-type B and C components of the stellar triple system visible in the background.

Another planet to orbit a small, M-type star is LTT 1445 A c. While the size of this planet is more typical of what astronomers find orbiting small stars, it is still an exciting system. It is one of two known planets in the LTT 1445 triple-star system, and both planets follow S-type orbits around the A stellar component. This means it orbits one star in a multiple-star system. LTT 1445 A c was discovered by the TESS mission in 2022, but in 2023 its diameter was measured to be 1.07 times Earth’s diameter using the Hubble Space Telescope. This rocky planet has a similar gravity to Earth and is the nearest Earth-sized transiting exoplanet. It’s just 22 light years away.

A screenshot from SpaceEngine showing the planet BEBOP-1 c with its two host stars. The planet is visible as a crescent, and cloudy stripes can be seen on its surface.

Cloud banding is visible on the illuminated crescent of the gas giant BEBOP-1 c, with its two host stars visible to the side.

Another type of planetary orbit in multi-star systems is the P-type orbit, where a planet orbits all of the stars in a system. Only 14 systems are known to host planets in P-type orbits, all of which are stellar binaries. Only two of these systems host multiple planets in P-type orbits. One of these multi-P-type systems includes BEBOP-1 (AKA TOI-1338). The planet BEBOP-1 c was discovered in 2023 and is the first planet in this type of orbit to be discovered using the radial velocity method, an indirect method of detecting exoplanets where astronomers look for periodic shifts in the spectrum of the host star. BEBOP-1 c is a gas giant planet, weighing around 65 times the mass of Earth, and has an orbital period around both of its host stars of 215 days.

A screenshot from SpaceEngine showing the planet LTT 9779 b with its host star. The planet is very close to the host star and it is very bright.

LTT 9779 b sits just 0.01679 AU from its G-type host, shining 80% of the incident light back to the star! Distances and sizes in this image are to scale.

Finally we end with a shining discovery from October of this year. LTT 9779 b is a Neptune-sized exoplanet orbiting a G-type main sequence star, originally discovered by the TESS mission in 2020. Further study of this planet in 2023 by the European Space Agency's Cheops Mission found  it is the shiniest planet ever discovered! Metallic clouds made of metals and silicates reflect 80% of the light from its host star. Astronomers quantify this reflectivity with a property called "albedo," the fraction of light reflected by a surface. There are a couple types of albedo, and LTT 9779 has a high "geometric albedo" of 0.8, even higher than the most reflective planet in the solar system, Venus, which has a geometric albedo of 0.689! Earth, by comparison, has a geometric albedo of about 0.434.

2023 was an exciting year for exoplanet discoveries! We hope you enjoyed this quick look at five discoveries that we found interesting, and we’re excited to see what 2024 has in store!

Further Reading:
TOI-1136: Astronomical Journal Article
TOI-5205 b: Space.com Article
LTT 1445 A c: NASA Press Release
BEBOP-1 c: Space.com Article
LTT 9779 b: ESA Press Release


  • Fixed minor bugs in the climate model
  • Updated exoplanets catalog
  • Updated asteroids catalog
  • Updated moons of Saturn