What is used to measure the distance of the earth from the sun

From Earth.

First, let's talk about parallax. What is parallax? Parallax is when an observer sees the same object at two different locations.

Difference in direction. Let's do a simple experiment: extend your right thumb, alternately close and open your eyes, and you will.

Noticed that the thumb is moving left and right towards the background. That's parallax. In engineering, trigonometric parallax is commonly used to measure distances.

can be completely determined.

Celestial objects can also be measured using the trigonometric parallax method. The key to it is to find the right side length a – because of the distance of the celestial bodies.

The distance is usually large – and the angle is precisely measured.

We know that the Earth moves annually around the Sun, which happens to meet the condition of the trigonometric parallax method: a long base.

lines and two different observation positions. Imagine that the Earth is on one side of the orbit and the other side, and the observer can perceive the constant.

Definition of poor. From a simple trigonometry relation, we can derive: r=a sin

Since the annual parallax of a star is usually less than 1°, (using the radian system) sin if we use the angle.

If the second is the annual parallax of the star, then the distance of the star is r=206 265a.

Usually, astronomers refer to the distance a from the sun to the earth as an astronomical unit (. Just measure the week of the star.

years of parallax, then their distance is determined. Of course, anniversary parallax is not necessarily easy to measure. Tycho also for the rest of his life.

The annual parallax of a star that is not observed – that is limited by the prevailing conditions at the time.

Astronomical units are actually very small distances, so astronomers came up with the parsecs (PC).

concept. That is, if the annual parallax of a star is 1 arc second (1 3600 seconds), then it is far from me.

We are 1 second apart. Obviously, 1 parsec is about 206265 astronomical unit.

Unfortunately, it is not possible to make a fairly accurate observation of annual parallax. Modern astronomy uses the trigonometric parallax method.

It is possible to accurately measure celestial objects within a few hundred parsecs, and no matter how far away, you have to sigh with admiration.

The second difference is to establish the distance between the two observation points on the earth as far away as possible, and then calculate the distance according to the triangle formed by the two observation points and the sun.

1.Gravitational force: f=gm1m2r times 1 2 (r and is dissociated).Quasi but not commonly used.

2.Triangle: Measuring angles at two different times of the year, using the hook bone theorem (at right angles).

3.Speed of light: 8 times 60 seconds times the speed of light.

calculated, according to the law of gravitation.

The distance between the sun and the earth cannot be measured directly, that is, the distance measurement through radar reflection cannot be used on the sun, because the sun itself is a plasma and cannot reflect measurable radar waves, so we can only measure the distance between the sun and the earth by indirect methods, scientists generally use the Venus transit method, but we need some known conditions before using this method. The ratio of the Earth's orbital radius to the orbital radius of Venus, fortunately,"Kepler's Planetary Law"It helped us solve this problem very early, and the ratio of the Earth's orbit to the orbit of Venus is so that we can use it to measure the distance from the transit of Venus.

<> when a transit of Venus occurs, we can look at Venus as a speck on the surface of the Sun. We take two points A and B on Earth and observe the position of Venus on the surface of the Sun at the same time. Due to the presence of parallax, the position of Venus at different positions on the surface of the Sun at the same time is different, which is denoted as a'and b'。

The distance between a and b is easily measured from the earth, a'and b'The distance between them can be calculated based on the ratio of the Earth's orbit to the orbit of Venus, i.e., ab a'b'＝。

This gives a from the true value of ab'b'The actual value, because the ratio of the two is not much different. Therefore, it is much more accurate to measure the A-B element. The next step is to photograph more Venus transiting through A and B at the same time** and then observe them together.

By comparing and calculating the diameter and a of the sun'b, the diameter of the sun can be obtained. Given the true diameter of the Sun, combined with its apparent diameter, we can calculate how far the Sun is from the Earth.

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The diameter of the sun imaged is relative to the diameter of the sun = the distance from the hole imaged by the sun to the distance from the hole to the sun – so that the distance from the sun to the hole can be found. The distance of the small hole is relatively close, which can be ignored, about equal to the distance from the sun to the earth.

We can measure the distance between the Sun and the Earth using the transit of Venus, plus the common knowledge that we all know, that is, the sun's rays, take 8 minutes and 18 seconds to travel to the Earth, and the distance can also be calculated from this number.

We can measure the distance between the sun and the earth through some professional means and astronomical research, and we should also pay attention to some comprehensive planning and measurement through professional data.

You can just hold a ruler and measure it.

1. Triangulation (also known as parallax method). The Earth orbits the Sun along an orbit with a diameter of about 300 million kilometers. Astronomers can observe a star one day and then look at the same star six months later, and find the difference in the perspective of the two star observations.

Using a very simple trigonometry principle, the distance from the star to the Earth can be calculated according to different perspectives.

2. The principle of the bright and quiet response measurement method is the Doppler effect.

3. The transit of Venus (that is, the Sun and Venus and the Earth are just in a straight line in the Lingye) means that a radar wave is emitted from the Earth, hits Venus, and then reflects back from Venus.

4. Use asteroids to measure the distance between the sun and the earth.

The average distance between the Sun and the Earth is about 100 million kilometers. The Sun is an ordinary star in the Milky Way, with an average distance of 149.6 million kilometers from the Earth, a diameter of 1.39 million kilometers, an average density of grams of cubic centimeters, a surface temperature of about 6,000 Ke, and a core temperature of 15 million Ke. From the inside to the outside, they are the solar nuclear reaction zone, the solar troposphere, and the solar atmosphere.

Thermonuclear reactions are constantly taking place in its central region, and the energy produced is radiated into space.

The Sun revolves around the center of the Milky Way. There may be a huge black hole at the center of the Milky Way, but it is surrounded by stars, so it looks like a "silver disk". These stars all revolve around the "silver core".

Unlike the Earth's orbit, these stars get closer to the "silver nucleus" with each orbit. The age of the Sun is about 4.6 billion years, and it can continue to burn for about 5 billion years.

The Sun is located on the spiral arm of Orion north of the galactic plane, about 30,000 light-years from the center of the Milky Way and about 26 light-years north of the galactic plane, and on the one hand it rotates around the galactic center at a speed of 250 kilometers per second for a period of about 100 million years, and on the other hand, it moves at a speed of kilometers per second relative to the surrounding stars in the direction of Vega. The Sun is also rotating, and its cycle is about 25 days in the equatorial zone of the Sun; The polar region is about 35 days.

Since the Earth's orbit is an ellipse, this is only an average, and at the nearest place, the Earth is 147 million kilometers from the Sun, and the farthest distance is 152 million kilometers.

In terms of light years, the distance between the sun and the earth is light years, because the distance between the sun and the earth is about 100 million kilometers, and the distance of 1 light year is trillion kilometers, which can be obtained by dividing the two. Based on the speed of light propagation, it is also possible to calculate the time it takes for sunlight to reach the earth, and it takes about 500 seconds for sunlight to travel to the earth.

The Earth is the third closest planet to the Sun in terms of distance from the Sun, and it is also the terrestrial planet with the largest diameter, mass and density in the solar system, at a distance of 100 million kilometers from the Sun.

The sun is a huge and hot planet of gas, and if it is too close to the sun, then the temperature of the earth will be very high, so that the moisture on the earth will not be retained, because it will soon be evaporated, and without water, it will not be suitable for human life.

Divide the knowledge and dig Xun class: science and engineering disciplines.

Problem description: It takes about 500 seconds for sunlight to reach the earth, so what is the distance from the earth to the sun?

Based on the data obtained, can you measure the diameter of the sun using the principle of aperture imaging? How is it measured?

Analysis: One astronomical unit scatter = meter kilometer.

Choose a large piece of cardboard and make a small hole in the middle, as small as possible, but the light that passes through this line can form a spot on the ground and can be seen.

At noon, make the small hole one meter above the ground. Measure the diameter r of the spot (as precise as possible). Let the diameter of the Sun be l.

There is l r = m 1 m where r is the measured value, and then it is enough to solve a one-dimensional equation.