"Recent archives show that there were countries looking for terrestrial planets many years ago, and they felt that they should be prepared in advance to deal with unknown crises, so as not to suddenly interrupt human civilization when an unknowable catastrophe arrives, which started even before the first space-time collapse. Hua Feng followed Sun Wukong into the archives room that day, and heard him talk eloquently about this past.

The nebula surrounding the Wolf-Laye star WR124 is located about 21,000 light-years from Earth. In the next few thousand to hundreds of millions of years, several large stars in the Milky Way are considered to be potential supernovae, including Snake XII, Seamount II, Ophiuchus RS, Scorpio U, KPD1930+2752, HD 179821, IRC+10420, Canis Major VY, Betelgeuse, Antares and Cornean Aldebares.

Many Wolf-Layet stars, such as Tiansha-1, WR 104, and members of the quintage cluster, are considered candidates to become supernovae in the "near" future.

The closest supernova candidate to Earth is the Pegasus IK (H.R. 8210), which is only 150 light-years away from Earth. It is a close binary star system consisting of a main-sequence star and a white dwarf, separated by only 31 million kilometers. The white dwarf is about 1.15 times the mass of the Sun, and in about a few million years the white dwarf will grow to a sufficient mass by accretion to evolve into a type Ia supernova.

In 2010, amateur astronomers Sun Guoyou and Gao Gao discovered a newly erupted supernova in the NGC5430 Galaxy, which was later confirmed by the famous Palomar Hill Observatory as a Type Ic supernova, numbered PTFacbu, which is also the first supernova discovered by astronomy enthusiasts in mainland China.

On February 19, 2011, amateur astronomers Kim Chang-wei and Gao Xing discovered supernova, 2011AJ.

On April 26, 2011, amateur astronomers Jin Changwei and Gao Xing discovered the superbright supernova, 2011by, with a maximum value of 12.5 magnitude, which is the brightest supernova in 2011 and relatively rare.

At 10 o'clock on September 12, 2015, Liao Jiaming, a fifth-grade student in Hefei, discovered a suspected supernova through the telescope of Xingming Wentai in Nanshan County, Xinjiang.

Earth-like planets are planets with silicate stone as the main component. They are very different from Jupiteroids in that those gas planets are mainly composed of hydrogen, helium, and water, and do not necessarily have a solid surface. The terrestrial planets have much the same structure: a metallic center dominated by iron, and an outer layer surrounded by a silicate mantle. Their surface generally has canyons, craters, mountains, and volcanoes.

On January 6, 2015, American astronomers issued a statement saying that 3 to 4 were theoretically identified as nearly the same size as the Earth and in the "Habitable Zone" (Goldilocks Zo).

e) of the planet, which means that there may be liquid water on it.

On July 19, 2017, the U.S. National Aeronautics and Space Administration (NASA) announced the discovery of 219 more suspected exoplanets (exopla

et), which includes 10 terrestrial planets in the habitable zone within their planetary system.

The eight planets are divided into three categories: terrestrial planets, giant planets, and perihelia.

Earth-like planets include Mercury, Earth, Mars, Venus. Earth-like planets are planets that are similar to Earth. They are close to the Sun, smaller in size and mass, have a higher average density, have a higher surface temperature, are about the size of the Earth, and are also made of rocks.

Terrestrial planets or their rocks can be terrestrial planets Terrestrial planets [2] are divided into two categories, one dominated by silicon compounds and the other dominated by carbides, such as asteroids containing carbonaceous chondrites. These two categories are called silicate planets and carbon planets (or "diamond stars"), respectively.

The solar system in which the Earth is located has four terrestrial planets: Mercury, Venus, Earth, and Mars, and a terrestrial dwarf planet, Ceres. Pluto, on the other hand, has a solid surface like a terrestrial planet, but is mainly composed of ice (see Ice Dwarf). When the solar system was formed, there should have been many more of these objects (microplanets), but they could all merge or be destroyed in the process of the formation of four gas giants in the solar nebula. Terrestrial planets, hydrosphere.

Almost all of the outer solar system planets found outside our solar system are gas giants for the simple reason that gas giants are large enough to be observed or inferred to exist. However, there are still a certain number of exoplanets that are suspected or confirmed to be terrestrial planets.

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The first terrestrial planet in the outer solar system has been detected. There are three planets orbiting the pulsar PSR B1257+12 with masses 0.02, 4.3 and 3.9 times that of Earth, respectively.

It was an unexpected discovery: their leap interrupted the pulsar's radio radiation. (If it weren't for the orbit passing in front of the pulsar, it wouldn't have been detected.) ）

When Pegasus 51b, the first exoplanet to orbit a fusion star, was discovered, many astronomers assumed that it was a massive terrestrial planet, because if it were a huge gas planet, it would not have been possible to be next to a star (0.052 AU) at such a distance. However, a similar exoplanet (HD 209458 b) was then measured in diameter, and the phenomenon of his transit indicates that these planets are indeed gas giants.

In June 2005, the first exoplanet was discovered next to the red dwarf star Gliese 876, 15 light-years away, which is almost certain to be a terrestrial planet. The mass of this planet is 5 to 7 times that of Earth, and the period of orbiting stars is only two Earth days.

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k (PLANET/RoboNet) and the Optical Gravity Lensing Experiment (OGLE), in the direction of Scorpio, 21,000 light-years from Earth, observed a cryogenic planet named OGLE-2005-BLG-390Lb, 5.5 times the mass of Earth.

The newly discovered planet, which orbits the parent star at a distance equivalent to the asteroid belt of the solar system, has been revealed by gravity microlensing. This unique ability allows the discovery of planets with Earth-mass as low as Earth's mass.

In April 2007, a team of 11 European scientists announced the discovery of an exoplanet in the habitable zone, with a temperature similar to that of Earth. The discovery was made using the European Southern Observatory's telescope in La Silla, Chile, where a special spectrometer can resolve oscillations in the spectrum of only a few wavelengths that could reveal the existence of other worlds.

They revealed the planet orbiting the red dwarf star Gliese 581, and the newly discovered planet was named Gliese 581 c, and inspired research into the wobble of equally faint stars, as 80% of Earth-like planets are found next to red dwarfs. The newly discovered planet, which is 5 times more massive than Earth, is classified as a super-Earth. The discoverer is not yet sure whether he is a rocky planet like Earth or a liquid water planet with a frozen surface.

If he were a rock like the Earth, it would be 1.5 times the diameter of the Earth according to the prevailing theories today, and it would be even larger if it was an ice hockey.

In the future, there will be a certain number of telescopes capable of directly observing terrestrial planets, including terrestrial planet seekers (Te

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ge Telescope，OWL）。 Astronomers also believe that many or most of the stars that approximate the Sun may have terrestrial planets nearby.

The density of an Earth planet refers to the average mass at zero pressure. The higher the density, the higher the metal content. The density of terrestrial planets decreases gradually as the distance from the star increases. The table below lists the terrestrial planets, the Moon, and the six largest asteroids in the solar system.

At the end of the 15th century, the great geographical discoveries initiated and completed by Spain and Portugal greatly expanded the world map. Immediately, the "land power empire" entered the decline, and the "sea power colonial empire" rose, and the earth became a whole from then on.

Since the 80s of the last century, the eyes of earthlings have begun to aim at planets outside the solar system. Since February 1995, the "Phoenix Project" has used the Parkes 64-meter radio telescope in New South Wales, Australia, to observe about 1,000 neighboring sun-like stars within 200 light years, but almost all of the more than 100 extrasolar planets found so far are composed of hot gases rather than Earth-like planets composed of rocks and minerals.

In December 2003, British scientists announced that a terrestrial planet similar to Earth may be orbiting Vega, a star 25 light-years away from Earth.

The biggest difficulty in finding extrasolar planets is that the planets themselves do not emit light, the reflected signals are extremely weak, and the light of the star is 1 million and 10 billion times brighter than the planets around it, and the light of the star must be shielded to highlight the characteristics of the planet. NASA is ready to address this issue on multiple fronts.

A Swiss and French astronomy team working at the La Silla Astronomical Observatory in Chile has discovered new terrestrial planets. The planet is about the size of Neptune, about seventeen times the mass of Earth, and it is about 20.5 light-years away from the solar system.

The planet is orbiting the red dwarf star G1 581 in the constellation Libra (the mass of the red dwarf G1 581 is about one-third the mass of the Sun). Astronomers have observed that it takes only five days to orbit the red dwarf.