Since it formed about 4.5 billion years ago, Earth has traveled about 450,000 light-years along its orbit around the Sun. A light-year is the distance light travels in one year, about 9.46 trillion kilometers. The 450,000-light-year figure is a calculation, not a measurement: it multiplies Earth's average speed around the Sun by its age.

Distance

This distance is the total length of the path Earth has followed around the Sun, counted relative to the Sun. Earth's orbit is nearly a circle, about 150 million kilometers (93 million miles) from the Sun, so each trip around covers about 940 million kilometers. One trip takes 365.256 days. Earth's average speed along its orbit is 29.78 kilometers per second, or about 107,000 kilometers per hour.

The U.S. Geological Survey gives Earth's age as 4.54 billion years, with an uncertainty of less than 1%. Multiplying the average speed by that age gives about 4.3 × 10¹⁸ kilometers, where 10¹⁸ is a 1 followed by 18 zeros. That is about 450,000 light-years. The uncertainty in Earth's age changes the total by less than 5,000 light-years either way.

The age itself marks when the solid bodies of the Solar System formed, rather than one exact moment when Earth was finished. So the figure is best read as a rounded total for Earth's whole history, not a precise count.

Size comparisons

• Earth moves about one ten-thousandth as fast as light. So in 4.5 billion years it has traveled as far as light travels in about 450,000 years.
• At its orbital speed, Earth covers the length of a marathon, 42.195 kilometers (26.2 miles), in about 1.4 seconds. It covers its own width, 12,742 kilometers (7,918 miles), in about 7 minutes.
• The whole journey is about four and a half times the width of the disk of the Milky Way, which is about 100,000 light-years across.
• It is a little less than one-fifth of the distance to the Andromeda Galaxy, about 2.5 million light-years.

Other ways to count the journey

Motion is always measured relative to something. Relative to the Sun, Earth travels in a closed loop and comes back to nearly the same place every year.

But the Sun also moves, carrying Earth and the other planets with it as it orbits the center of the Milky Way. NASA gives the Solar System's average speed around the galaxy as about 720,000 kilometers per hour. One trip around takes about 230 million years.

If the Sun had kept that pace for 4.54 billion years, it would have gone around the galaxy about 20 times. Along the way it would have traveled about 3 million light-years, nearly seven times as far as Earth's path around the Sun. That is farther than the distance to the Andromeda Galaxy, but the path curves around the Milky Way instead of leading away from it.

Sources

• Earth Fact Sheet. NASA, 2024.
• Age of the Earth. U.S. Geological Survey.
• Sun: Facts. NASA Science, 2026.
• Measuring the Universe. International Astronomical Union.
• Speed of light in vacuum. NIST CODATA, 2022.
• Marathon. World Athletics.
• Our Milky Way Galaxy: How Big is Space?. NASA Science, 2024.
• Messier 31 (The Andromeda Galaxy). NASA Science, 2026.