The sunspots appear to be traveling at a rate of roughly 12 degrees each day. Now we're ready to answer the BIG question: how long does it appear to take the Sun to complete a full 360-degree rotation? * However, keep in mind that the Earth revolves around the Sun in the same direction at a rate of around 1 degree every day (almost 365 days to circle the Sun), so the apparent movement of the Sun is actually quite small. It takes the Sun about 400 days to rotate completely.
Here's how you calculate the time it takes for the Sun to rotate 360 degrees:
First, find the distance between the Sun and the Earth in miles. Divide this number by 0.5 to get the radius of the Sun in miles. Then multiply this number by 60 to get the hours required to rotate the Sun completely.
For example, if the distance between the Sun and Earth is 100 miles, then the radius of the Sun is 508,400 miles or 524,900 kilometers. Multiply this number by 60 to get 300 million hours (or months). The Sun will appear to move westward across the sky as it moves from north to south across the celestial sphere. During this time, the Earth travels eastward across its orbit at a rate of nearly 30,000 miles per hour, completing one full revolution in just under 29 days.
The earth revolves, giving the impression that the sun is moving. The Earth takes about 24 hours to complete one full rotation, thus the sun seems to move at a rate of 15 degrees each hour. Around 15 degrees each hour, or about 0.25 degrees per minute. This is equal to half the apparent size of the sun as viewed from Earth every 12 minutes.
From solstice to solstice the amount it moves will vary because during a year the earth is not exactly aligned with the sun. But on average the amount will be about 15 degrees east or west of north.
This is important because without this correction, all times between sunrise and sunset would be the same throughout the year, which they are not. If nothing corrected the image above, after a month there would be no afternoon sunshine, only morning and evening sunlight.
People have been making observations about the movement of the sun for thousands of years using everything from naked eye observation to sophisticated equipment. Over time these observations have led to estimates being made about how long ago certain events in the history of Earth took place. An example is the estimate that based on the amount the sun appears to move across the sky in 4 hours, humans first arrived in Australia about 40,000 years ago rather than 7 million years ago as previously thought.
The Earth rotates once every 24 hours, but because the sun isn't a physical entity like a planet, its rotation is more difficult to locate. According to NASA, because the sun is a ball of gas and plasma, it does not have to revolve as tightly as solid planets and moons. As a result, there is an angle between the sun's equatorial plane (the plane that divides the solar system into two equal parts) and the Earth's orbit.
You might wonder why the sun doesn't just spin faster so that its equator is perpendicular to the Earth's orbit. The answer has to do with gravity. Because gravity travels at the speed of light, the farther away something is, the slower it will appear to be spinning. For example, if you were on the surface of the sun and looked up at one of its stars, you would see it moving slowly across the sky because light from this star reaches you after traveling through the entire sun. If the star was closer to the sun, it would look like it was moving faster because less time has passed since it was first illuminated by the sun.
This same effect is what allows us to see objects that are far away from us move more quickly than those that are close by. On August 26, 1609, Dutch astronomer Edmond Halley predicted that a comet would reappear in 1758, which it did.
The sun spins on its axis once every 27 days on average. Sunspots form when the sun's plasma interacts with its magnetic field, resulting in solar flares and various forms of solar storms. Sunspots appear to be hot, but they are really cold patches on the sun's surface, however the term "cold" is relative. They can become very hot indeed if they are about to erupt.
Eruptions that lead to eruptions occur when a spot's magnetic field becomes so strong that it pulls on other parts of the photosphere. This causes these regions to rise up into view above the rest of the spot, much like the eruption of an old-growth tree after being cut down near the ground. Once this happens, more intense radiation flows out from the spot into space.
Eruptive spots often produce high-speed particles that reach Earth before they do, which leads to geomagnetic storms. These can cause power outages by damaging electrical equipment, and they may also cause heat waves at high levels in the atmosphere. If a storm gets severe enough, it can even trigger earthquakes!
Sunspots come in two main types: active and inactive. An active sunspot has all the features of a normal sunspot except it is constantly changing. It grows and sheds material all the time, usually driven by magnetic forces. As it does so, new loops are created that eventually fall back down onto the spot itself, only to be raised up again later on.