What might Planet Nine look like? Assuming this planet-like object really does exist out there, Planet Nine's mass would most likely be a magnitude (roughly 10 times) greater than Earth's, with a girth approaching the range of one of our ice giants.
The object, which the researchers have nicknamed "Planet Nine," could have a mass about 10 times that of Earth and orbit about 20 times farther from the Sun on average than Neptune. It may take between 10,000 and 20,000 Earth years to make one full orbit around the Sun.
Planet Nine is unnamed, unconfirmed, and unknown. We haven't been able to detect it, and we don't even know for sure that if we did spot it, it would even be a planet. It might be a special kind of black hole, or be made entirely of dark matter.
But they could as easily be primordial black holes floating around the galaxy, the astronomers proposed. If that were the case, the putative Planet Nine could well be a black hole, too, in a distant orbit around the sun.
Planet 9 continues to remain elusive. This potential super-Earth-sized object in the outer Solar System is only hypothetical, as something out there appears to be gravitationally influencing several Kuiper Belt Objects into unusual orbits.
There is a lot of evidence for the planet – thought to be up to 20 times further out from the Sun than Neptune – but it may be impossible to see with current technology. The giant, hidden planet is thought to be 10 times larger than Earth and on an orbit that takes 10,000 or 20,000 years to go round the sun.
Because Eris appeared to be larger than Pluto, NASA initially described it as the Solar System's tenth planet.
The scientists assume that the planet is a small ice giant with an envelope of hydrogen and helium. With their evolution model they calculated how parameters like the planetary radius or the brightness evolved over time since the Solar System has formed 4.6 billion years ago.
"Black holes do not go around in space eating stars, moons and planets. Earth will not fall into a black hole because no black hole is close enough to the solar system for Earth to do that," NASA noted in 2018, adding that the sun isn't big enough to become a black hole.
When was the last time all nine planets aligned? In 1982, all nine of the planets were on the same side of the Sun, scattered over some 90 degrees. According to Star Walk, the next full alignment will occur on May 19, 2161, when eight planets will be located within 69 degrees from each other.
The strength of an object's gravitational pull is proportional to how much mass it has. Because the sun is losing mass, its pull on Earth is weakening, leading our planet to drift away from our star by about 2.36 inches (6 centimeters) per year, DiGiorgio said.
This speculative "Planet 9," according to estimates, would be about 5-10 Earth-masses in size and orbit about 400-800 au from the Sun. A planet at this distance would be extremely difficult to spot in normal optical sky searches because of its faintness, even to telescopes like PanSTARRS and LSST.
Venus is often called "Earth's twin" because they're similar in size and structure, but Venus has extreme surface heat and a dense, toxic atmosphere. If the Sun were as tall as a typical front door, Earth and Venus would each be about the size of a nickel.
According to the paper, Planet Nine might be host to up to 20 moons, each up to 62 miles (100 kilometers) across.
Jupiter is a stormy planet that is probably best known for its Great Red Spot. The spot is actually a giant, wild storm that has been raging for more than 300 years.
Is it possible for a black hole to "eat" an entire galaxy? No. There is no way a black hole would eat an entire galaxy. The gravitational reach of supermassive black holes contained in the middle of galaxies is large, but not nearly large enough for eating the whole galaxy.
Despite their abundance, there is no reason to panic: black holes will not devour Earth nor the Universe. It is incredibly unlikely that Earth would ever fall into a black hole. This is because, at a distance, their gravitational pull is no more compelling than a star of the same mass.
We are in absolutely no danger from black holes. They're a bit like tigers – it's a bad idea to stick your head in their mouth, but you're probably not going to meet one on your way to the shops. Unlike tigers, black holes don't hunt. They're not roaming around space eating stars and planets.
In 1930, Pluto was discovered and officially named the ninth planet.
Assuming that it is a smaller version of the ice giants Uranus and Neptune, with hydrogen and helium dominating its atmosphere, the pair calculated that a 10-Earth-mass Planet Nine would be about 3.7 times wider than our planet. Temperatures would average minus 375 degrees Fahrenheit (minus 226 degrees Celsius).
(The Earth and sun are on average, 93 million miles or 150 million kilometers apart.) A small planet so far away would be tough to spot in optical searches because the world would see very little sunlight at such great orbital distances.
Astronomers have announced the discovery of the 100th planet known to inhabit another solar system. The star is 100 light years from Earth in the southern constellation Grus, or The Crane. The planet, one and a half times the mass of Jupiter, has a roughly circular orbit, like those of the sun's family of planets.
Neptune is dark, cold, and very windy. It's the last of the planets in our solar system.
Psyche was discovered by Italian astronomer Annibale de Gasparis on March 17, 1852. He named the asteroid for Psyche, the Greek goddess of the soul who was born mortal and married Eros (Roman Cupid), the god of Love.