Are you used to seeing the step-by-step planets in the solar system, do you know that there are many strange planets in the universe? Let’s get to know each other today.
There are currently eight planets in the solar system, and their trajectories do not overlap with each other, and there is a huge gap between them, just like a group of strangers who have never met in their lives. But in other galaxies, some planets don’t, and they often come together in what seems like a big party.
Astronomers have found six planets of the star TOI-178, about 200 light-years from Earth, by studying data from NASA’s Transiting Exoplanet Survey Satellite (TESS). Astronomers once thought the star had only two planets, but recent research has found four more. The reason why these six planets are so difficult to find is that they often “come together” so that the refracted light overlaps each other, as if emitted by the same star.
Five of the six planets share similar orbits, orbiting TOI-178 in periods of 3, 6, 10, 15 and 20 days, respectively. This means that they line up from time to time, such that the first planet will overlap the second planet once when it goes around the second planet, the third planet will meet the second planet when it goes 3/5 times around, and so on. Whenever at this time, the light of a certain planet is blocked, astronomers cannot find the blocked planet.
This phenomenon is unimaginable in the solar system, because Mercury, Venus, Earth, and Mars are similar in size and density. Once their trajectories are so similar, it is easy to “collision” accidents and tear each other into pieces. In the TOI-178 galaxy, the size of the planets is not much different, the diameter is about 1.1 to 3 times that of the earth, but the density is far apart, some are terrestrial planets, but its neighbors are only half the density of Neptune loose gaseous planets. This arrangement allows them to follow close trajectories without colliding.
If there are living beings living on one of these planets, they will often watch wonderful astronomical phenomena such as solar eclipses and “five stars in a row”.
All the planets in the solar system have only one “father”, and that is our sun. But what happens if there are planets orbiting multiple stars?
In fact, in the universe, it is not uncommon for two stars to have a similar distance and revolve around each other. Some astronomers even believe that there are many more binary star systems than single star systems like the solar system. However, planets orbiting multiple stars are rare, perhaps because planets orbiting in such a system are really “extreme sports”, and it is easy to lose their bones.
HD-131399Ab with three “fathers” (imagination)
NASA’s Kepler space telescope has made great contributions in the process of searching for binary star systems. It has discovered many binary star systems and their planets. For example, among the few binary star planets that have been discovered so far, it has found Three such as Kepler-16b, Kepler-47b and Kepler-47c. Binary planets are generally inhospitable to life, especially if they are too close to their star, such as Kepler-47b. The distance between Kepler-47b and the host star is much smaller than the distance between Mercury and the sun. Living things living on this planet will quickly die of high temperature and lack of oxygen.
Being far from the stars is not necessarily a good thing. The masses of the double stars Kepler-16A and Kepler-16B orbiting Kepler-16b are 69% and 20% of the mass of the sun, respectively. These two stars are very close to each other, and the average distance between the earth and the sun is only one fifth. The similar mass and distance lead to their closer gravitational pull to Kepler-16b, so Kepler-16b is like a tug-of-war line, being pulled to one side and sometimes to the other by the gravitational pull of the two stars. In this way, the trajectory of the planet will continue to change. Sometimes it may be extremely far away from the star, and the weather will become extremely cold;
Living on the Duozu planet, it will be difficult to see the night. When the planet moves to one end of its orbit and begins to move towards another star, this star will suddenly rise from the other end of the sky, and sometimes you can see See the strange sight of multiple “suns” hanging in the sky at the same time. HD-131399Ab is 340 light-years away from Earth, and it orbits three stars at the same time. The revolution period of HD-131399Ab is 550 Earth years. Due to its many “fathers”, the average sunset will only come once in half a planetary year, that is to say, it takes 275 years on Earth to see a sunset. .
In our solar system, the large planets are far away from each other, each surrounded by much smaller moons. Scientists believe that this structure is formed because dust clumps gathered in protoplanetary disks around young stars evolved into rocky chunks; these rocky chunks absorbed material in orbit and eventually became planets, and the remaining material formed satellite.
However, according to this rough description, what kind of star can be called a planet, and what kind of star can be called a satellite? In the planetary system, planets and satellites are distinguished according to their orbits. Those that directly orbit a star are planets, and those that orbit a planet are satellites. However, the case of double stars blurs the distinction between planets and satellites. If two planets orbiting each other are very close in size, they will undoubtedly be classified as binary planets; if the size difference is very large, the small stars are satellites; Between the first two cases, that is, when the two stars are of the same size but have certain differences, it is difficult to distinguish them.
For example, we once mistakenly thought that Pluto, which was the ninth planet in the solar system, was “expelled” from planetary status because more and more stars with the same mass as it or even slightly larger than it were discovered. In this case, should Charon, a moon with a similar mass to Pluto, still be called a satellite?
The orbit of the planet HR 5183b is very elongated
The International Astronomical Union Congress held in 2006 confirmed the new status of Pluto: dwarf planet. But so far, the location of Charon is still controversial, some people think it is a dwarf planet, some people think it is a satellite. In fact, because the difference in mass is not too great, the gravitational center of Pluto and Charon is not above Pluto, but falls outside these two celestial bodies, so one of them is not really revolving around the other, according to the new By planetary standards, Charon can also be identified as a dwarf planet. In this way, orbiting Pluto and Charon would become the solar system’s first confirmed pair of double planets, two planets orbiting each other like a ballroom dance.
If there are such double planets in a certain corner of the universe, and they are all in the habitable zone, for example, the earth has a twin brother, will life evolve in these two binary stars? What interesting stories will happen to the double star and the life in it? Let us look forward to more discoveries by astronomers.
Are the orbits of planets always elliptical or nearly circular? This is not the case, such as the planet HR 5183b discovered by astronomers about 100 light-years from Earth. The planet’s trajectory resembles a giant boomerang, in the shape of an extremely long ring. If this kind of orbit is compared with the orbits of the planets in the solar system, half a circle of HR 5183b is equivalent to moving from beyond Neptune to the vicinity of Jupiter, so that its revolution period also fluctuates between 45 and 100 Earth years, In other words, the seasons and climate of HR 5183b are unpredictable.
The reason for this is that astronomers speculate that there was once a large star near HR 5183b, and its gravity deflected the exoplanet. It is known that giant planets initially form in circular orbits, aligned with the host star’s equatorial plane. As a star system evolves, if a planet’s orbit is disturbed by other large objects in the same system, it is likely that its orbit will become less and less circular.
The change in the shape of the planet’s orbit may be even more dramatic. When a planet flies past its host star, in each close encounter, the tidal force between the planet and the host star increases sharply, and the uneven force between the perihelion and aphelion of the planet’s orbit will cause the orbit become more elongated.
According to this law, astronomers have calculated the orbital inclination angles of nearly a hundred exoplanets, among which 36 planets have inclination angles exceeding 20 degrees and orbit their host stars in a long and narrow ellipse. But so far, HR 5183b remains the only planet astronomers have discovered orbiting its host star in such an extreme orbit.
The universe is huge, and the stars in it also have all kinds of peculiarities, far beyond human imagination. This is why the exploration of the universe is fascinating.