Hubble is famous for its use to observe distant depths of the universe, but occasionally to observe the interior of the solar system, such as in 1994, when Hubble observed Comet Shoemaker Levi 9 colliding with Jupiter.
Hubble recently discovered that a comet, numbered C/2014 UN271 (a comet made up mainly of ice and solid dust, is coming toward Earth at a speed of 9.7 kilometers per second, and is now about 3.2 billion kilometers away.
What is the concept of 3.2 billion kilometers? The Earth is 150 million kilometers away from the Sun, which is about 21.3 times the average distance between the Sun and the Earth. It takes 177 minutes for sunlight to travel through this distance, so it can be seen that the comet is indeed far away from us.
C/2014 UN271 Also has a special orbit, instead of flying towards Earth along the ecliptic plane (the plane of the Earth's orbit), it maintains a large angle with the ecliptic plane.
The comet was first discovered by astronomers in 2014 and is also known as Comet Bernardinelli-Bernenstein. It deserves vigilance because it is the largest comet in the solar system discovered by humans, with a diameter of up to 137 kilometers and an estimated mass of about 500 trillion tons.
After research on the sudden extinction of dinosaurs from Earth 65 million years ago, scientists generally believe that the extinction event was related to an asteroid impact, with a crater about 180 kilometers in diameter on what is now the Yucatan Peninsula in Central America, and the asteroid that hit Earth was about 10 kilometers in diameter. C/2014 UN271 is 13.7 times the diameter of the comet, if it does collide with the Earth, the consequences will be unimaginable, and human civilization may disappear.
Worrying about the sky seems absurd, but the facts tell us that although the sky will not collapse, it is not absolutely safe overhead, and it is really necessary to guard against foreign objects. In 2013, there was a small object fall in the Chelyabinsk region of Russia, although the diameter of this small object is only about 15 meters, but the destructive force is not small at all.
In addition to the sun and the eight planets in the solar system, there are also a large number of small bodies such as asteroids and comets.
Between Mars and Jupiter there is an asteroid belt, in which about 500,000 small objects of varying sizes are concentrated. Beyond neptune's orbit is the Kuiper Belt, which is also a small celestial gathering area.
However, the Kuiper Belt is not the edge of the solar system, and scientists speculate that there is an Oort cloud beyond the Kuiper Belt. It is estimated that the sum of the masses of the small bodies of the Oort Cloud is about 5 to 100 times the mass of the Earth (the error is indeed very large). It is a globular cloud that envelops the solar system and is the true boundary of the solar system. If this is the boundary, the diameter of the solar system will be 1 light-year.
Although its existence has not yet been strongly confirmed, scientists believe that the Oort Cloud has existed since the beginning of the solar system, and it is the scrap material left at the edge of the solar system during the formation of the sun and the eight planets, which is filled with many active comets, and the C/2014 UN271 comet comes from.
Comet cycles are short and long, bounded by a 200-year period and a short period within 200 years, with the comet number prefixed with "P/"; longer than 200 years with a prefix of "C/". It has been suggested that long-period comets may come from the Oort Cloud, while short-period comets may come from the Kuiper Belt.
C/2014 UN271 Comet is one of the longest-orbiting comets ever discovered, with aphelions located deep in space 54,000 AU (1 AU, approximately 150 million kilometers, i.e., the average distance between the Sun and the Earth), apparently from the outermost region of the Oort Cloud.
These asteroids and comets have their own orbits and usually don't fly around, but they have small masses and low inertia, which also means that their orbits are easily drifted by the gravitational perturbations of other celestial bodies. In the unlikely event that they break into the Earth's orbit and get too close to it, they could collide with the Earth. Although the probability of this happening is very low, it can't stand the number of ah.
For now, comet C/2014 UN271, although it is coming to Earth, is still far from Earth, and from its current trajectory, it will reach perihelion in 2031, when it is about 1.6 billion kilometers away from the Sun, outside the orbit of Saturn, and poses no threat to Earth.
However, C/2014 UN271 This super comet still deserves our continuous attention, after all, it is too big, in case of other celestial influences, the flight trajectory changes, it may pass by the Earth, or even collide with the Earth.
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