6. HR 5183 b: A planet with a strange orbit
HR 5183 b is an exoplanet 3 times the mass of the largest planet in the Solar System – Jupiter. This unique planet has a very eccentric orbit. While most planets have circular orbits, this giant planet has an egg-shaped orbit.
Astronomers have been observing HR 5183 b for 20 years with three telescopes, but have yet to see the planet complete a complete orbit. They estimate that this could take between 45-100 Earth years .
Very eccentric orbits like these have been observed before, but usually by planets and objects much closer to their host stars.
7. OGLE-2016-BLG-1928: Rogue Exoplanet
Astronomers believe that the Milky Way may contain many “orphans” in the universe – planets that have escaped from their host stars to drift freely through the universe alone.
Exoplanets are often detected through their impact on host stars, so these “homeless” planets are almost undetectable. That’s what makes the discovery of the rogue exoplanet OGLE-2016-BLG-1928 as it roams the Milky Way so special. Although it is not the first rogue planet discovered, it is the smallest, most difficult to detect.
OGLE-2016-BLG-1928 was discovered in late 2020 using a technique called gravitational magnification.
8. TOI-178 planetary system: A harmonious and chaotic planetary system
At first glance, the TOI-178 planetary system might look like any other set of worlds. But a closer and longer observation shows that at least five of the system’s six worlds are locked in a rhythmic dance with each other.
The 5 outer planets have an 18:9:6:4:3 resonance. This means that when the first planet in the sequence – the planet closest to the host star compared to the other 4 – completes 18 orbits, the 2nd completes 9, the 3rd completes 6, the 4th planet completes 4 and the 5th planet – the planet furthest from the host star – completes 3.
This complex series of resonances could potentially indicate a planetary system that has not been disturbed by gravitational interactions or collisions with other systems since its formation.
However, where we find order in the universe, there is often chaos as well. The components of the planets that make up the TOI-178 system do not show harmony. Next to a world with a dense Earth-like ground is a planet with a “puffy” low-density ground, followed by an exoplanet with a density similar to Neptune.
9. 55 Cancri e: The Universe’s Most Valuable Exoplanet
55 Cancri e takes under 18 hours to complete one orbit and has a temperature of 2,300 degrees Celsius. The composition of this planet makes it so distinct and perhaps the most valuable object in the universe.
According to NASA , 55 Cancri e is twice the size of Earth, but has nearly nine times the mass. That has led astronomers to think that this super-Earth may consist of high-pressure carbon in the form of graphite and diamond mixed with some iron and other substances.
The estimated value of 55 Cancri e is believed to be 384 million times the Gross Domestic Product (GDP) of the Earth in 2011.
10. Blanets: The Extreme Planet of a Black Hole
The most extreme exoplanets may not form around stars at all, instead orbiting supermassive black holes – such planets are called blanets. They form from the gravitational collapse of overly dense regions of protoplanetary dust clouds and supermassive black holes at the centers of active galactic nuclei (AGNs).
Currently, there is no evidence that planets orbiting black holes actually exist, but dynamic modeling studies of disks of gas and dust show that under certain conditions, the formation of black holes does not exist. Planetary formation will occur in such regions.
If that were to happen, the blanets would form at a much farther distance from the black hole than most of the distance between the planets and the host star. So far that it could take 1 million Earth years for such a world to complete one orbit.
