How did people discover extrasolar planets?

Xiao Yuanyuan said too professionally, it is difficult to understand, I will explain two to you here.

4. Transit method.

On the earth, it is impossible to directly observe the planets outside the solar system in the distance with light, but we can directly observe the stars, when a planet revolves around the star, the transit phenomenon generally occurs, that is, the planet in the process of motion, to a certain extent obscuring the light of the star, at this time, in our field of vision, the light of the star will flash at a certain frequency, we can determine through this frequency, whether the star has a planet, and the orbital speed of the planet's mass revolution.

5. Gravity microlensing method.

Light is refracted as if it were a lens after being subjected to gravity by the mass of a celestial body. This is known as "gravitational lensing". For example, we can observe a variety of different images of the entire Milky Way cluster against the background of galaxies.

When the refraction of light is small, the current science and technology cannot distinguish the image of the galaxy presented, and the gravitational lens at this time is also called the gravitational microlens.

As a result, the stars in the back are affected by the celestial bodies in front of them, and their light appears brighter.

If the star in front of it (the lenticular object) is a planet, the role of the lens will be more pronounced due to the close proximity of the two.

This method of detection using the action of gravity lens is called "gravity microlensing".

These are the two best ways to explain, the others are too professional, I know what to say, but I don't know how to explain it to you, check it yourself.

Astronomers generally look for exoplanets in indirect ways compared to their parent stars, which tend to obscure the appearance of exoplanets, and there are six successful indirect methods.

1. Astrometry.

2. Radial velocity method.

3. Pulsar timing.

4. Transit method.

5. Gravity microlensing method.

6. Stellar disk method.

For more information, please see the link below.

If it is considered that the planets move in a uniform circle around the Sun, then the gravitational pull f of the Sun on the planets should be the centripetal force experienced by the planets, i.e.

f=mv^2/r

where r is the distance between the sun and the planet, v is the linear velocity of the planet's motion, and m is the mass of the planet.

The relation v=2 r t of the period t and velocity v in circular motion

Substituting the above equation is f=4 2(r 3 t 2)m r 2

According to Kepler's description of the laws of planetary motion, r 3 t 2 is a constant, so it can be concluded that the gravitational force between the planet and the sun is directly proportional to the mass of the planet and inversely proportional to the quadratic of the distance from the planet to the sun.

According to Newton's third law, the force of a planet to attract the Sun is equal in magnitude and has the same properties as the force of the Sun to attract a planet. Newton believed that since this gravitational force is proportional to the mass of the planet, it should of course also be proportional to the mass of the sun. Therefore, if you use m'Indicates the mass of the sun, then there is.

f∞m'm/r^2

Written as an equation, it is f=gm'm/r^2

g is a constant, which is the same for any planet.

Newton also studied the motion of the moon around the earth and found that the gravitational pull between them followed the same law as the gravitational pull between the sun and the planets.

Newton studied the gravitational attraction of many different objects that follow the same law, and further extended this law to any two objects in nature, officially publishing the law of universal gravitation in 1687

Any two objects in nature are attracted to each other, and the magnitude of the gravitational force is directly proportional to the product of the masses of the two objects and inversely proportional to the quadratic of their distance.

If m1 and m2 are used to denote the masses of two objects, and r is used to denote their distance, then, the law of universal gravitation can be expressed by the following formula:

f=gm1m2/r^2

The unit of mass is kg, the unit of distance is m, and the unit of force is used as a constant, which is called the gravitational constant, which applies to any two objects, and it is numerically equal to the interaction force when two objects with a mass of 1kg are 1m apart, and the standard slow value of the gravitational constant is g=

Usually taken. g=6367*10^-11nm^2/kg^2

In descending order, they are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

If the distance from the Earth to the Sun is 1, the distance from each planet to the Sun is: .

If the solar system is reduced by a factor of 100 million, the distance from each planet to the Sun is (in meters).

The solar system has Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Mercury: the average daily distance is 57910000 km

Venus: Average daily altitude 108200000 km

Earth: Average daily distance 149600000 km

Mars: Average daily distance 227,940,000 km

Jupiter: Average daily distance 778,330,000 km

Saturn: Average daily distance 1429.4 million km

Uranus: Average daily altitude 287099 million km

Neptune: Average daily altitude 4504000 km

The planets of the solar system revolve around the sun, and the solar system is part of the Milky Way, and the extragalactic galaxy is on the same level as the Milky Way, what kind of planet are you talking about? Please refer to the cosmic galaxy diagram.

Map of the Milky Way galaxy and the map of the solar galaxy, why don't you look for the nine planets of the solar system (it should be ten now)?

According to the current definition, there are eight planets in the solar system, namely Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Above is a schematic diagram of their size and the true proportions of the orbital distance.

Here's a schematic diagram of their current location (April 20, 2016), ****:

At present, the vast majority of scientists around the world believe that life does exist outside the solar system. It's just that in the distant universe, if you want to explore extraterrestrial life, it is indeed not easy, as far as the current scientific and technological means are concerned, it is still relatively difficult to detect extraterrestrial life, at least before the development of new technologies, it is difficult to directly detect extraterrestrial life, and can only be judged by the characteristics of some planets, or to speculate whether there will be life on the planet. <>

The earth is a sphere with liquid water, and it is precisely because of this that the earth will give birth to a lot of life, if you look at the problem from this perspective, then as long as liquid water is found on the planet in the universe, then there is a high probability that new life will appear on the planet, of course, this is not absolute. For example, many scientists now speculate that new life will emerge in Trappist-1. The reason for this is that there is indeed some liquid water on each planet in the Trappist-1 area, and the temperature is not too cold, so it is very likely that life will be born.

Of course, this is just a speculation by scientists, or a speculation. Although this star system is located behind the Milky Way, there is no way to determine whether there is water in the atmosphere of this galaxy with current scientific methods, so it is difficult to determine whether there will be new life. <>

With our current scientific methods, it is basically unrealistic to want to completely or completely detect the universe. At present, the cosmic world we have spied on may only be the tip of the iceberg in the entire universe, but science is advancing, and I believe that in the future, human beings will definitely explore more cosmic space, and even conquer the entire universe.

Scientists use high-tech means and telescopes to detect new life in the distant extrasystem, and they also judge through some scientific research methods.

I think scientists use advanced detectors to detect life on distant exoplanets, so I admire those scientists.

Scientists analyzed and calculated the signals they observed through radio telescopes, and finally looked at whether these high-end creatures were emitting signals.

Scientists have developed a lot of technology, put some detectors on it, and through these professional equipment, they can detect life.