The Discovery History of Interstellar Migration

March-April 200614 A group of astronomers specializing in "idolize" discovered a planet very similar to the Earth in the depths of the Milky Way, which is probably the key to finding a new home for life. This planet is 9000 light years away from the solar system, its volume is about 13 times that of the earth, and its mass is similar to that of Neptune. It runs around a red dwarf star, which is its "sun", half smaller than the sun and much cooler.

At first, scientists thought it was just an ordinary earth-like planet, but after research, it was found that this planet was strikingly similar to the earth, just like a replica of the earth. According to scientists' speculation, the overall structure of this planet is quite similar to that of the earth. The "inner heart" is also a rock core like the earth, and the outer layer is wrapped with rocks and other components. But its surface temperature is slightly lower, and there is no liquid water on it but frozen ice. Therefore, this planet is also called "super earth". Scientists at the Geneva Observatory in Switzerland announced at the academic conference held in France on June 16, 2008 that they had discovered five new "super earths". Among the five "super-earths" discovered this time, three are located in the direction of easels and swordfish, 42 light years away from the earth, and their mass is 4.2 times, 6.7 times and 9.4 times that of the earth respectively. These three "super earths" revolve around a star slightly smaller than the sun. Period of revolution is 4 days, 10 and 20 days respectively. The fourth "super earth" revolves around the star HD 18 1433 with a period of 9.5 days. The star HD 18 1433 also attracts a planet similar to Jupiter, and the period of revolution lasts for three years. The fifth "super earth" has 22 times the mass of the earth and revolves once every four days.

Since 1995 discovered the first "super earth", astronomers have successively detected more than 270, most of which are as huge as Jupiter and Saturn, and few planets are similar in size to the earth. Because most "super-Earths" are too far away from us, astronomers can't directly observe them with the naked eye through ordinary astronomical telescopes, and can only "indirectly measure" the existence of "super-Earths" through detection means such as radio waves or spectral analysis. June 5438+February 65438+June 2009, according to American media reports, an international research team composed of American and Australian scientists recently discovered that there are four terrestrial planets in two adjacent sun-like star systems, two of which are called "super-earths". Researchers believe that this discovery will provide important clues for human beings to find habitable planets, and the hope of finding habitable planets will greatly increase in the next few years.

A habitable planet may be discovered in a few years.

Among these four terrestrial planets, two are called "super-earths", which are more massive than the earth, but less massive than Uranus and Neptune. The existence of these "super-earths" shows that it is only a matter of time before a livable planet similar to Earth is found.

Among the four newly discovered terrestrial planets, three are located around the star "6 1 virgo". The star "6 1 Virgo" is actually equivalent to the twin brother of the sun, 28 light years away from the earth and located in Virgo. At this time of year, people can observe Virgo for several hours in the night sky before the sun rises. The researchers estimated the possible minimum masses of the three planets. Chris Tinney, a member of the research team and an astronomer at the University of New South Wales in Australia, believes that the minimum mass of "6 1 Vir b" is about 5. 1 times that of the earth, and the mass of "6 1 Vir c" is about 18 times that of the earth. Tinny believes that "the mass of the smallest planet is just within the mass range of the super earth. This is the first time that a planet of this size has been found around a sun-like star. " Previously, scientists have found "super earth" around other stars, but those stars are much colder than the sun.

On February 22, 2009, astronomers discovered an Earth-like planet orbiting a dim star, only 40 light years away from the Earth. It was a steaming "water world". Astronomers believe that this planet is closer to the earth than any exoplanet previously discovered outside the solar system.

Beijing, China, 12, 2009 17/ Sina Science and Technology reported that astronomers found an earth-like planet orbiting a dim star, only 40 light years away from the earth. It is a steaming "water world" with a volume six times that of the earth. It is believed that 75% of the earth's surface is covered with water, but because of its high temperature, it cannot support the existence of life on earth. There is evidence that this "water world" also has an atmosphere. Astronomers believe that this planet is closer to the earth than any exoplanet previously discovered outside the solar system.

By measuring the brightness reduction caused by the passing of the planet, scientists can calculate the density of the planet and make wise guesses about its composition. The newly discovered planet is named "GJ 12 14b". It is believed that three quarters of the surface is covered with water and ice, and only one quarter of the surface is rock.

Chakri Berta, a graduate student and astronomer at Harvard-Smithsonian Center, discovered this water planet. He said: "Despite the high temperature, this is still a world with water. Compared with any other known exoplanet, this planet is smaller, colder and closer to the Earth. "

Scientists believe that there must be something blocking the light from the parent star except the surface of GJ 12 14b, and there may be an atmosphere composed of hydrogen and helium around it. With the help of the Hubble Space Telescope, astronomers can determine the composition of the planet. David Charbonneau, director of the Mills project, said: "Since this planet is very close to the Earth, Hubble should be able to detect the atmosphere and determine its composition. With luck, it will be the first super earth with a proven atmosphere, although this atmosphere may not be as friendly to life as we know. "

This discovery was published in the journal Nature on June 6th, 65438. Professor Jeffrey Marcy, a famous planet hunter and a professor at the University of California, USA, speculated on the possible scenes of this water world in an article published in Nature magazine. He wrote: "It may have a very deep ocean and should be liquid. Due to the heat given by the parent star, its surface temperature reaches about 190 degrees Celsius. In addition, a steam atmosphere similar to a sauna may also exist. " The kepler mission was launched in March last year. It was designed to help find planets outside our solar system. Its working principle is "occultation observation"-when one or several planets pass in front of their parent star, the light of the star is partially blocked, and its brightness will decrease slightly accordingly. Through the unprecedented accurate photometry of Kepler telescope, we can detect this brightness change and infer the existence of occultation, that is, planets.

After analyzing the data of Kepler telescope in the past seven months, the team of scientists at Harvard Smithsonian Center for Astrophysics discovered two planetary targets, which revolve around a star numbered Kepler -9. This star is about 2300 light years away from the earth.

One of the planets numbered Kepler -9b has an orbital period of only 19 days around its parent star. The other one, Kepler -9C, takes 39 days to make a revolution.

The researchers found that the orbits of the two planets changed periodically. This means that there is a "gravitational vibration" between the two planets-their gravitational interaction affects their respective orbital characteristics. Using these data, researchers can calculate the mass of two planets. The calculation results show that these two planets are gas giant planets slightly heavier than Saturn.

But when the researchers tried to explain the brightness loss of the central parent star by the size of these two planets, they were surprised to find another faint occultation star. The weak signal detected indicates that there is a smaller planet in this galaxy with an orbit closer to the parent star. Its orbit period of revolution is 1.6 days. The mass of this planet is about 1.5 earths, and it is a terrestrial planet made of rocks.

But researchers can't celebrate yet, because such a weak signal has many interference factors. The background star or companion star in binary system will also produce similar signal effect. "So far, we can only say that we have found a very interesting signal, and we hope we can get more information soon," Matt holman said. He is the chief scientist of this research.

But even if this signal turns out to be an Earth-like planet, it is unlikely that humans will want to emigrate there: according to its orbital position, the surface temperature of this planet is about 1900 degrees Celsius. On September 29th, 20 10, astronomers from the National Science Foundation of the United States announced the discovery of a planet which is the most similar to the Earth so far, and its environment and temperature in some areas are suitable for human habitation.

This planet named Gliese 58 1g is located in Libra and orbits the red star Gliese 58 1, which is much smaller than the sun. The star is 20 light-years away from the Earth, and astronomers found that there are six planets orbiting Gliese 58 1. The other five (Gliese 58 1b to Gliese 58 1f) are not located in the "habitable zone" (habitable zone), but this one is located in the habitable zone, and its temperature is neither too hot nor too cold, so liquid water can form oceans, lakes and rivers.

Gliese 58 1g is probably a rocky planet with water and atmosphere on its surface. Its diameter is about 1.2 to 1.4 times that of the earth, and its mass is about 3. 1 to 4.3 times that of the earth. Its gravity is close to the earth, and the average surface temperature is between -3 1 and-10. The temperature of the red dwarf star it surrounds is only 1/50 of that of the sun, and its volume is 1/3 of that of the sun. Gliese 58 1g orbits its "sun" for only 37 days. One side of Gliese 581g is always facing the "sunshine" and the other side is always in darkness. Therefore, its sunny side may be very hot, the temperature can reach more than 100 degrees, and the temperature of the backlight side can be tens of degrees below zero.

For living or future human immigrants, the most suitable place is the "gray" zone-the transition zone between darkness and light in Gliese 581g. According to their different longitudes, many life can find a stable climate suitable for their emergence and evolution.

Astronomers have discovered nearly 500 planets outside our solar system. However, they are almost too big, made of gas instead of rock, and the temperature is either too hot or too cold for our life. Justin, an astronomer at Pennsylvania State University, said, "This is the first planet that really excites me." He thinks this planet is very suitable for breeding life.

Finding life on other planets does not mean finding aliens, but even finding a single-celled bacterium on another planet will shake the view that life on earth is unique. However, we still have many unsolved mysteries about this planet. Scientists can't confirm whether there is water on it and what is its atmospheric composition, but because its environment is very suitable for the existence of liquid water, and there seems to be life where there is water on the earth, Justin thinks that "the possibility of life on this planet is 100%".

Relatively speaking, the time to find this planet is not long and the difficulty is not great. Astronomers believe that there are millions of such terrestrial planets waiting for us to explore. Gliese 58 1g was discovered according to the observation results of Hawaiian W.M. Keck Observatory 1 1 year. The combination of modern advanced science and technology and traditional ground telescopes continues to play an important role in exploring exoplanets. 20 1 1 At the beginning of May, an international team of astronomers composed of Massachusetts Institute of Technology, Columbia University, Harvard University and Santa Cruz, California officially announced the discovery results: a "super earth" was discovered in a planetary system 40 light years away from the Earth at 55 Cancri, which was discovered through the MOST space telescope in Canada, 60% larger than the Earth and 8 times the mass of the Earth.

The artist's "super earth"

The planet number is: 55 Cancri e, which surrounds the star number 55 Cancri A, and it only takes 18 hours to make a revolution. In other words, you don't need a calendar to live on this planet, just remember to bring a watch. And the sun you see is 60 times bigger and 3600 times brighter than what you see on the earth. The surface temperature of this planet is 2700 degrees Celsius. Astronomers at MIT believe that there can be no atmospheric structure at such a high temperature, but some scientists believe that gravity is strong enough to retain part of the atmosphere. Because of the high brightness of the main star, many sensitive measurements can be made. For scientists, the planet is a perfect laboratory, which can comprehensively study the formation, evolution and whole life cycle of the planet.

However, this planet cannot be directly observed, even with a powerful telescope. The star in this planetary system, 55 Cancri A, can be observed with the naked eye in the next two months if it is on a clear night.

A planetary system consisting of 55 Cancer stars. The first planet was discovered by a research team in California in 1997, and it was named 55can CRI B. In the following five years, the team discovered two other planets, namely 55 Cancri c and 55can CRI D. In 2004, the research team in Texas discovered 55 Cancri e, and the latest one was discovered in 2008, which is also the fifth planet in the planetary system.

The discovery process of these five planets is based on Doppler technology. Stars will swing due to the gravity of nearby planets, and then the parameters of the planets can be determined by measuring the change of starlight wavelength. Last year, Rebekah, a Ph.D. student in astronomy at Harvard University, and Daniel, an exo-astrophysicist in Santa Cruz, California, reanalyzed the data in 2004 and thought that the orbital period of 55 Cancri e was shorter than originally thought. Later, Wayne of the Massachusetts Institute of Technology and astronomer Matt holman of the Smithsonian Center for Astrophysics applied to use the MOST space telescope for observation. It is found that the transit period is only 17 hours 4 1 minute, which is consistent with the previous analysis, while the light of the star is only dimmed by 1/5000 in each transit. These data also conclude that the diameter of this planet is about 2 1000 km, which is about 60% larger than the earth.

This discovery excited Professor Matthews, an astronomer at Columbia University: Just like Captain Kirk did in Star Trek, we (science) will eventually catch up with science fiction. 20 13 In August, researchers at the Massachusetts Institute of Technology (MIT) discovered an exoplanet with a very short orbital period. [1] is rapidly rotating around a star named Kepler -78 in Cygnus. After calculation, it is found that its size, mass and even composition are very similar to those of the earth. This is the first time that a planet so similar to the earth has been discovered. Therefore, astronomers call this planet "Earth Brothers". On April 20th14-04-18, American scientists discovered the terrestrial planet Kepler-186f outside the solar system, and its terrestrial degree is the highest among the terrestrial planets discovered so far.

It is reported that scientists from the National Aeronautics and Space Administration (NASA) of the United States discovered this earth-like planet by using the Kepler mission and named it Kepler-186f. It is about the size of the earth, and it runs around Kepler-186 in an orbit suitable for human habitation.

David Charbonneau, an exoplanet expert from Harvard University, pointed out that Kepler-186f is 500 light years away from the Earth, which is "one of the most important discoveries" in Kepler's mission. Although it is known that it is 10% larger than the earth, its composition needs to be further explored. Elisa Quintana, the chief researcher from Ames Research Center of NASA, further pointed out that "Kepler-186f is located in a livable zone with moderate radiation intensity and stellar frequency, which means that it is likely to have an atmosphere like Earth, and there may be water and liquid water on its surface. By the end of 2009, man has discovered more than 270 planets that revolve around the stars like the earth. Among these planets, a considerable part of them weigh between 5 times and 15 times of the earth's weight, and many of these "super-earths" are made of rocks like the earth. They also have an atmosphere and a rocky surface, unlike Jupiter, which is a gas planet. Some of them are not very old, and the temperature on their surfaces varies greatly. Scientists believe that these "super earths" were formed in a "snowstorm" in the universe. Only these snowstorms can cover these planets with thick ice in the past hundreds of thousands of years, so that these planets can survive until now.

All these "super earths" have their own astrolabes and atmospheres, some of which revolve around a star. One side of the rocky planet near the star is warm, while the other side is very cold. When these planets are young, the stars around them are relatively stable. As they continue to grow, the temperature will also change. It is impossible for human beings to immigrate to those planets with current technology. If human beings want to emigrate to other planets before the earth is destroyed, they must first protect the earth.