10 Lesser-Known Facts about Planets

Planets are significantly smaller as compared to stars present in the universe. Although they feature some fascinating and unique features like texture, atmosphere, elements present, rings, etc. We’re blessed with discovering new phenomena on planets or about planets every now and then. The following is a similar list of 10 lesser-known facts about planets. 

1. Scientists believe that there is a ninth planet in our solar system that is 10 times the size of the Earth. The location of the planet has not been confirmed yet but it is sure that it exists because of its gravitational effects on other objects. 

Hypothetical Planet 9
Hypothetical Planet 9

Also known as “Planet 9,” it has 10 times greater mass than the Earth, and it travels along an elongated orbit that is located at 400 times the Earth’s distance from the Sun. The orbit of Planet 9 is also probably 15 to 25 degrees off the main orbital plane of the solar system where the rest of the planets travel. 

The idea of the existence of the new planet was proposed back in 2014, and it soon gained popularity among astronomers. The speculations are based on patterns of objects in a ring of debris in the outer belt known as the “Kuiper Belt.” 

It was noticed that the objects here were clumped together in a fashion that suggests the presence of gravitational force from some big body. Since this finding, evidence has only gotten stronger for Planet 9. 

The only alternative that is known so far that contradicts this theory is our lack of understanding of the Kuiper Belt. Researchers suggest that the clustering that we discovered might be the result of “self-gravity” and not another planet. (Source)

2. There is an exoplanet named J1407b that has more than 30 rings, and each of them is tens of millions of kilometers in diameter. The rings are 200 times larger than Saturn’s. 

J1407b
Image credits: Ase19el/Wikimedia

The star or the exoplanet is too far to observe its rings directly, although we can make a detailed model of its ring system. 

Researchers mentioned that if we could replace the rings around Saturn with the ones around J1407b, we could easily see them at night. This is because they would be many times larger than our moon. Not just its rings, but the planet itself is much larger than Saturn and even Jupiter. It is approximately the equivalent of 10 to 40 Jupiter masses. 

The young planet with the heavy rings was discovered in 2012. Recent studies have not only reasoned the formation of rings but also estimated their mass. 

The conclusion was that the ring system has a long, 120 million kilometer diameter, which roughly has a mass equal to the Earth in the form of light-obscuring dust particles. 

It orbits a Sun-like star, but 95% of its light is blocked by J1407b’s own ring system. Astronomers have predicted that the rings will get thinner in the next several million years. (Source)

3. An index was developed in 2015 that suggests Earth is not the most habitable planet found yet. There is a rocky exoplanet named Kepler-442b, 1,100 light-years away from us that is roughly the same size as Earth. This planet has a habitable rating of 0.836 whereas Earth has 0.829. 

Size comparison Kepler-442b and Earth
Size comparison Kepler-442b and Earth. Image credits: Ph03nix1986/Wikimedia

The new scale that determines the habitability of planets is based on previous selection methods that primarily relied on the “Goldilocks Zone.” It is the correct distance from its sun to allow liquid water to exist. 

Not just the distance from the sun or the star, the new index also takes into account the rockiness of the planets. It suggests that the rockier a planet, the more habitable it is. 

Moreover, the new index includes the eccentricity of planets’ orbits and their albedo. More eccentricity of orbits means that the planet can receive uneven and sometimes extreme amounts of heat and light from its star. And, albedo is the amount of solar energy reflected off by the planet’s atmosphere.

It is said that a calculator will be invented for the use of exoplanetary researchers on the web. This will help them figure out the habitability figure of any given planet just by entering some data. (Source)

4. The planet Mars has the longest valley known. It is the Valles Marineris which is 4,000 kilometers long. It is 10 times longer than the Grand Canyon or as long as the US. Researchers aren’t sure how this longest valley was formed. 

3d rendered illustration of the mars – Valles Marineris

Valles Marineris on the red planet takes around a fifth of the planet’s circumference. At some points, it spreads as wide as 200 kilometers and gets 10 kilometers deep. 

If we compare the valley to its Earth’s counterpart, the Grand Canyon is only 446 kilometers long, a maximum of 30 kilometers wide, and 1.6 kilometers deep. 

On Mars, the valley stretches from east to west and is located just below the equator. In the west, it starts from Noctis Labyrinthus and terminates near the Chryse Planitia basin. 

The canyon system features a variety of terrain in its formation like collapsing pits and massive deserts. It is full of cracks in the crust, cliffs, walls, landslides, all along the way.  

Scientists have attempted to theorize multiple explanations for the formation of Valles Marineris. However, the most widely accepted cause is the volcanoes in the Tharsis region. 

When observed from Earth using a telescope, the canyon appears to be a dark scarring on Mar’s surface. (Source)

5. The most mass that a planet can have is equal to 13 times the mass of Jupiter. After this certain point, the planet’s own gravity will start to cause a nuclear fusion reaction, and the body would be categorized as a “brown dwarf” or “failed star.” 



Jupiter, the largest planet in our solar system, is so large that if we gather all other planets into a single mass, Jupiter would still be 2.5 times greater. Also, it is important to note that large planets like Jupiter are just too small to be considered stars. 

A standard definition of a star is a body that is large enough to fuse hydrogen into helium in its core. Stars are mostly made up of these two elements and the same goes with large planets. 

However, in large planets, there is no fusion because they’re in a state of hydrostatic equilibrium. This phenomenon prevents the planets to create any fusion.

For a planet to become a star, it must have at least 80 times the mass of Jupiter. But there are objects that fall between the category of planets and stars like the “brown dwarfs.” 

Brown dwarfs are star-like, and they don’t show hydrostatic equilibrium. And, a planet needs to have 13 times Jupiter’s mass to become one. (Source)

Also read: 10 Strange Facts About Space You Probably Didn’t Know

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