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# how far is the earth from the sun

## how far is the earth from the sun

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## how far is the earth from the sun,

The Sun is at an average distance of about 93,000,000 miles (150 million kilometers) away from Earth. It is so far away that light from the Sun, traveling at a speed of 186,000 miles (300,000 kilometers) per second, takes about 8 minutes to reach us. Like all of the other planets in our Solar System, Earth does not travel around the Sun in a perfect circle. Instead its orbit is elliptical, like a stretched circle, with the Sun just off the center of the orbit. This means that the distance between Earth and the Sun changes during a year. At its closest, the Sun is 91.4 million miles (147.1 million km) away from us. At its farthest, the Sun is 94.5 million miles (152.1 million km) away. The Earth is closest to the Sun during winter in the northern hemisphere.

In other words,

The distance between the sun and the earth is 150.82 million km.

• The distance is referred to as one astronomical unit-the distance light travels in about eight and a half minutes. The distance between the Earth and the Sun varies slightly over the course of the year.
• The sun is the nearest star to earth. It is continuously emitting heat and light. It is the main source of heat and light energy for all planets in our solar system.
• In our solar system, the Earth is the only habitable planet. The existence of life on Earth is attributed to a number of ideal factors, including the presence of an atmosphere and water, as well as the appropriate distance from the sun. The earth appears bluish green from outer space as light from the landmass and water bodies gets reflected.

### measure the distance

Historically, the first person to measure the distance to the sun was the Greek astronomer Aristarchus around the year 250 B.C. He used the phases of the moon to measure the sizes and distances of the sun and moon.

During a half moon, the three celestial bodies should form a right angle. By measuring the angle at Earth between the sun and moon, he determined the sun was 19 times as far from the planet as the moon, and thus 19 times as big. In fact, the sun is about 400 times larger than the moon.

“Aristarchus’ measurement was probably off because first, it is hard to determine the exact centers of the sun and the moon and second, it is hard to know exactly when the moon is half full,” according to Cornell University’s astronomy website.

Although imprecise, Aristarchus provided a simple understanding of the sizes and distances of the three bodies, which led him to conclude that the Earth goes around the sun, about 1,700 years before Nicolaus Copernicus proposed his heliocentric model of the solar system.

In 1653, astronomer Christiaan Huygens calculated the distance from Earth to the sun. He used the phases of Venus to find the angles in a Venus-Earth-sun triangle. For example, when Venus appears half illuminated by the sun, the three bodies form a right triangle from Earth’s perspective.

#### measure

Guessing (correctly, by chance) the size of Venus, Huygens was able to determine the distance from Venus to Earth, and knowing that distance, plus the angles made by the triangle, he was able to measure the distance to the sun. However, because Huygens’ method was partly guesswork and not completely scientifically grounded, he usually doesn’t get the credit.

In 1672, Giovanni Cassini used a method involving parallax, or angular difference, to find the distance to Mars and at the same time figured out the distance to the sun. He sent a colleague, Jean Richer, to French Guiana while he stayed in Paris. They took measurements of the position of Mars relative to background stars, and triangulated those measurements with the known distance between Paris and French Guiana. Once they had the distance to Mars, they could also calculate the distance to the sun. Since his methods were more scientific, he usually gets the credit.

“Expressing distances in the astronomical unit allowed astronomers to overcome the difficulty of measuring distances in some physical unit,” astronomer Nicole Capitaine of Paris University told Space.com. “Such a practice was useful for many years, because astronomers were not able to make distance measurements in the solar system as precisely as they could measure angles.”

### Relevant Outcome of Numbers

Distance between earth and sun, a = around 150 million km, defined as one Astronomical Unit (AU).
Radius of the Sun, Rsun = around 700,000 km.
Orbital speed of Earth, v = around 30 km/s.

### How Does Our Distance From the Sun Affect the Earth?

When they learn that our distance from the sun is variable, some people think that this is the cause of the seasons. This conclusion seems logical, but it is mistaken. The change in distance is so minute that it has a minimal actual effect on climate. It does have some effect – however, this is negligible. The Earth is slightly cooler at perihelion and slightly warmer at aphelion.

### Modern Equation

With the advanced technology and sophisticated spacecraft and radar, there are now direct methods of measuring the distance between the Sun and the Earth. By applying the old methods, the value of au changes according to the location of an observer in the solar system. Moreover, the measurement depended on the mass of the Sun,

and since the Sun’s mass changes as it emits energy, the value of au also changes. In August 2012,

the International Astronomical Union voted to change the definition of au to the plain old number,

92,955,807 miles, which is based on the light’s speed and a fixed distance without taking into account the Sun’s mass.

### Orbiting the sun

It’s a fair question—how long does it take for the earth to orbit the sun? But when you stop to think about it for a moment, you’ll realize that you likely already know the answer. It takes one year, or 365.256 days (in the case of a sidereal year), to complete its rotation. “The farther away something is from the sun,

the slower it travels around the sun,” says Benjamin Studevent, a physics teacher at St. Francis School in Louisville, Kentucky. “It doesn’t just take longer because it has a longer trip; it actually travels at a slower speed.” If you’re curious about more strange mysteries surrounding our planet, read up on these unsolved questions.

### Light years

Robert Burnham noticed that, quite by coincidence, the number of astronomical units in one light-year and the number of inches in one mile are virtually the same.

For general reference, there are 63,000 astronomical units in one light-year, and 63,360 inches (160,000 cm) in one mile (1.6 km).

This wonderful coincidence enables us to bring the light-year down to Earth. If we scale the astronomical unit – the Earth-sun distance – at one inch, then the light-year on this scale represents one mile (1.6 km).

The closest star to Earth, other than the sun, is Alpha Centauri at some 4.4 light-years away. Scaling the Earth-sun distance at one inch places this star at 4.4 miles (7 km) distant.

### Sunlight summary

Most of us take for granted that sunlight just naturally appears. But it has to travel the distance from the sun to the earth in order for us to enjoy those rays.  it takes sunlight 8 minutes, 20 seconds to make the trip. The site explains how scientists came up with this number. First, you must know that Earth orbits the sun at a distance of approximately 150 million km. Light moves at 300,000 km per second. When one divides these numbers, the result is 500 seconds. That translates into 8 minutes, 20 seconds.

### The fastest-moving stuff in the universe

As mentioned above, light travels at an incredible 186,000 miles per second (300,000 km/sec). That’s very fast. If you could travel at the speed of light,

you would be able to circle the Earth’s equator about 7.5 times in just one second!

In other words, a light-second is the distance light travels in one second,

or 7.5 times the distance around Earth’s equator. A light-year is the distance light travels in one year.

How far is that? Multiply the number of seconds in one year by the number of miles or kilometers that light travels in one second, and there you have it: one light-year. It’s about 5.9 trillion miles (9.5 trillion km).

### Earth’s orbit slightly affects length of the season

Though not responsible for the seasons, Earth’s closest and farthest points to the sun do affect seasonal lengths. When the Earth comes closest to the sun for the year,

as we do every year in early January, our world is moving fastest in orbit. Earth is rushing along now at almost 19 miles per second (30.3 km/sec), moving about 0.6 miles per second (one km/sec) faster than when Earth is farthest from the sun in early July. Thus, the Northern Hemisphere winter and – simultaneously – the Southern Hemisphere summer are the shortest seasons as Earth rushes from the solstice in December to the equinox in March.

In the Northern Hemisphere, the summer season (June solstice to September equinox) lasts nearly five days longer than our winter season. And, of course,

the corresponding seasons in the Southern Hemisphere are opposite. Southern Hemisphere winter is nearly five days longer than Southern Hemisphere summer.