How do astronomers calculate the distance between earth and sun? Firstly, what we actually measure is basically the distance from the earth to any other body for example Venus. Moreover, we use things that we know regarding the relations between the interplanetary distances.

However, we transmit a radar signal at another planet i.e. moon or asteroid. Finally, we measure how long it takes for the radar echo to return from there. Before the radar system, astronomers were relying on other less direct geometrical methods.

What is the Distance Between Earth and Sun?

howfarisearthfromthesun
The sun is present at the heart of our solar system. All the bodies there in the solar system are planets, asteroids, comets and many more. These bodies revolve around the solar system at different distances from each other.

In addition, mercury, the planet that is the closest to the sun gets as close as about 29 million miles that are around 47 million kilometres. It is in the elliptical orbit. Whereas many other objects are there in the Oort cloud, that is the solar system’s icy shell.

These lies about as far as 9.3 trillion miles that are around 15 trillion kilometres. But actually what is the distance between the earth and the sun? The Earth orbits the sun at around 100,000 times closer than the Oort cloud.

It is a nearby average of 92,955,807 miles that is around 149,597,870 Km. distance between earth and sun is known as an astronomical unit or we can call it AU. We also use it for measuring distances all over the solar system.

How Long Would It Take to Get to the Sun From Earth?

It’s tough to predict a spacecraft’s journey towards the Sun. If we were to launch an imaginary spacecraft from Earth that would travel around 153,454 mi / 246,960 km per hour constantly, it would reach the Sun in 606 hours, or 25 days.

However, what clouds our estimation is the fact that it is impossible to launch a spacecraft that would constantly maintain its top speed from the start. When the spacecraft is launched, it will take several minutes or hours to reach its top speed.

One of the fastest planned spacecraft on Earth is the Parker Solar Probe. This probe might reach a maximum speed of 430,000 mi / 692,017 km per hour. This means that the spaceship may get to the Sun in around 216 hours or nine days.

However, there is an additional problem. Nothing in space stays still, so we can’t launch anything directly at the Sun, because the moment the object would arrive at the Sun’s position, it would no longer be there.

How to Measure distance between Earth and Sun?

Firstly, we have to find the relative distance between the earth and other planets as well. So, let us assume that the distance between the earth and the sun is ‘A’. Now, we will consider the orbit of Venus.

To the first approximation, the orbits of Venus and the Earth are perfectly round or circles around the sun. The orbits present here are on the same plane. It is sure that there are two places where the sun, Venus and the earth have angle equally at 90 degrees.

The two points present here indicate the greatest and the major elongation of Venus. These points are the farthest from the sun that results in the visibility of Venus in the sky.

Another way for understanding this is to have a look at the motion of the venus in the sky relative to the sun. When Venus orbits the sun, it gets away from the sun in the sky. It reaches a maximum apparent separation from the sun.

Finally, it goes towards the sun again. This is the cause that the venus is never visible in the evening for more than about 3 hours after the sunset or in the morning for more than 3 hours before the sun rises.

The first rigorous and exact scientific measurement of the distance between earth and sun was found by Cassini in 1672 by parallax measurements of Mars. Mars was observed from two places simultaneously by Cassini and another astronomer.

Is Earth Getting Closer to the Sun?

howfarisearthfromthesun
Since the Sun is so far away, and as discussed above, it would take more than a lifetime to reach it, would our chances of getting to the Sun increase in the distant future? Is our Earth getting closer to the Sun?

Now, getting closer to the Sun wouldn’t really help us in any way, shape, or form, probably not even scientifically. There may be other methods available to us in the future to collect data from our Sun, without the need to be near it.
In fact, we aren’t even getting closer to our Sun. Our Earth is actually slowly moving away from the Sun. This is because our Sun, like all stars, burns its fuel.

As the Sun burns its fuel, it loses power, mass, and gravity. Since the Sun’s gravity / gravitational pull is weakening, since it loses mass, our Earth can slowly move away from it.
Our Earth is moving away from the Sun at around 15 cm every year. However, Earth will never escape from the Solar System, since the Sun will evolve in 5 billion years into a red giant star.

When this happens, Earth will be with 750,000 km / 466,028 mi farther away from the Sun; however, the Sun will also expand its radius for more than 256 times its current size (696,340 km / 432,685 mi), reaching over 178 million km / 110 million mi in radius, inevitably engulfing Earth in the end.

How Far is it From Earth to Space?

howfarisearthfromthesun
If you want to reach space from Earth, then you would have to fly straight up in the sky for around 100 km / 62 miles. This is where most scientists agree, is where our planet’s boundary ends, and suborbital space begins.

Did you know?

  • Our Solar System travels through space at a speed of around 515,000 mph / 828,000 km/h.
  • It takes our Solar System around 230 million years to travel around our galaxy, the Milky Way, once.
  • Neptune is the farthest planet from the Sun. It is situated at around 30 AU away – that’s 30 times farther away from the Sun than our Earth.
  • Though Neptune is regarded as the farthest planet away from the Sun when Pluto was categorized as a planet, it held this title. Now Pluto is considered a dwarf planet, and it is located at around 39 AU away from our Sun.

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