In fact, our Sun is only 20 years old: how is this possible and what is a galactic year?

It takes approximately 220-230 million Earth years for the Sun to orbit the Milky Way galaxy, a period of time astronomers call a galactic year. And if we were to use this unit of measurement, the Sun would be about 20 years old now.

People are used to counting time by measuring the Earth's motion relative to the Sun. But this movement is quite insignificant compared to the rotation of the Sun and the entire solar system around the center of the Milky Way, Live Science writes.

According to Keith Hawkins, an assistant professor of astronomy at the University of Texas at Austin, a major U.S. research center, it takes approximately 220-230 million Earth years for the Sun to rotate around the Milky Way galaxy. And if we were to measure time by this galactic "clock," the Earth would be approximately 16 years old now, and the Universe would be 60 years old.

The motion of the solar system around the galaxy is similar to the Earth's orbit around the Sun. But instead of orbiting a star, the Sun orbits a supermassive black hole that lies at the center of the Milky Way and is held in orbit by a great deal of gravity, Hawkins says.

"The sun is moving at about 230 kilometers per second, which is equivalent to 500,000 miles per hour. This makes it possible to orbit around the center of the galaxy and not be pulled into a black hole," the scientist notes.

Compared to the Earth year, the galactic year represents time on a large scale, but it is not a consistent measurement across the galaxy. And what Earthlings call a galactic year depends on the Earth's position in the Milky Way spiral.

"We would say that a galactic year is 220, 230 million years. Other stars in the galaxy have a different galactic year," Hawkins says.

As the astronomer explained, the galaxy is about 100,000 light-years wide, and the Earth is located about 28,000 light years from its center. And if you imagine the galaxy as a city, then the Earth is located somewhere near the suburbs. For stars orbiting near a black hole - the center of the "city" - the galactic year is relatively short, and in the "suburbs" where our solar system lies, galactic years are slightly longer."

For example, Mercury, the inner planet of our solar system, makes a complete revolution around the Sun in about 88 Earth days. Uranus, the seventh planet from the Sun, orbits the Sun every 84 years by Earth's standards. The distant dwarf planet Pluto takes 248 Earth years to complete one orbital cycle.

According to Hawkins, astronomers have established the length of the galactic year by observing the movement of stars through the galaxy and drawing conclusions about their speed and motion. This is quite a fundamental science that became clear at the beginning of modern astronomy.

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