How long does the earth take to revolve around the sun?

Question: How long does the earth take to revolve around the sun?

One of the most common questions that people ask about astronomy is how long does it take for the Earth to complete one orbit around the Sun. The answer is not as simple as you might think, because there are different ways to measure the length of a year.

The most familiar way to define a year is based on the seasons, which are caused by the tilt of the Earth's axis. This is called a tropical year, and it is about 365.24 days long. However, this is not the same as the time it takes for the Earth to return to the same position relative to the Sun, which is called a sidereal year. A sidereal year is slightly shorter than a tropical year, about 365.26 days, because the Earth's orbit is not perfectly circular and the Sun moves slightly relative to the distant stars.

Another way to define a year is based on the alignment of the Earth, the Sun and a fixed point in space, such as the vernal equinox. This is called an anomalistic year, and it is about 365.26 days long. This is the time it takes for the Earth to go from one perihelion (the closest point to the Sun) to the next. An anomalistic year is slightly longer than a sidereal year, because the Earth's orbit is slightly elliptical and the perihelion shifts over time due to gravitational perturbations from other planets.

As you can see, there is no single answer to how long does the Earth take to revolve around the Sun, but rather different ways of measuring it depending on what you are interested in. The difference between these types of years may seem small, but they have important implications for calendars, seasons and astronomical phenomena. In this blog post, we will explore these topics in more detail and explain why we use the tropical year as the basis for our calendar.