The sun moves across the sky in such a predictable manner that you would never suspect that its relationship with the Earth is changing all the time. In fact, the average distance between Earth and the Sun is not constant from year to year. so do we know Earth Getting closer or farther from the Sun? And what forces are at work on our planet and our star to make this happen?
In short, Sunday With time, it is getting away from the earth. On average, Earth is about 93 million miles (150 million kilometers) from the Sun, according to nasa (opens in new tab), However, its orbit is not perfectly circular; It is slightly elliptical, or oval shaped. This means that the Earth’s distance from the Sun can range from about 91.4 million to 94.5 million miles (147.1 million to 152.1 million km). NASA (opens in new tab) it is said.
Nevertheless, the distance between the Earth and the Sun has been gradually increasing over time, on average. There are two main reasons for this increasing distance. One is that the Sun is losing mass. The other includes the same forces that cause of tide on the earth.
related: When will the sun rise?
the sun is shrinking
atom fusion The reactions that power the Sun convert mass into energy following Einstein’s famous equation e = mc^2, Because the Sun is constantly producing energy, it is also constantly losing its mass. during the rest of the Sun’s lifetime – an estimated 5 billion years or so, according to nasa (opens in new tab) — Models of how stars evolve over time predict that the sun will lose about 0.1% of its total mass before dying, Brian DiGiorgio, an astronomer at the University of California, Santa Cruz, told Live Science in an email.
Although 0.1% may not sound like a lot, “it’s a lot of mass,” DiGiorgio said. “It’s about the same amount of mass JupiterAccording to, Jupiter, in turn, has about 318 times the mass of Earth. Exploratorium (opens in new tab) in California.
The force of gravitational pull of an object is proportional to its mass. Because the Sun is losing mass, its pull on Earth is weakening, causing our planet to move away from our star about 2.36 inches (6 centimeters) per year, DiGiorgio said. But we shouldn’t be giving Sooraj a lavish travel party just yet.
“It’s very negligible, especially compared to the general variation in Earth’s orbital distance that is caused by its slightly elliptical orbit — about 3%,” DiGiorgio said.
tidal effect
in the form of bus MoonTides occur on Earth as a result of gravitational pull, so the Earth’s gravity Tug on the sun. It spans the part of the Sun that faces Earth, resulting in a “tidal bulge,” wrote Britt Scheringhausen, an associate professor of physics and astronomy at Beloit College in Wisconsin, for Cornell University. ask an astronomer (opens in new tab) Page.
The Sun revolves around its axis once in about 27 days. according to nasa (opens in new tab), Since this is faster than the 365 or more days it takes the Earth to complete one orbit around the Sun, the tidal bulge produced on the Sun ahead of the Earth sits in front of the Earth. The mass of the bulge has a gravitational pull, which pulls Earth farther in its orbit and pushes it away from the Sun, Scheringhausen noted. (a similar effect is leading Earth’s moon will slowly move away from our planet (opens in new tab),
However, these tidal forces have a very weak effect on Earth’s orbit: they cause the Earth to move about 0.0001 inches (0.0003 cm) away from the Sun each year, DiGiorgio calculated.
Any major change in climate?
Can Earth’s increasing distance from the Sun affect Earth’s climate?
“As the Earth moves away from the Sun, the sunlight will dim,” DiGiorgio said. Noting that Earth’s distance from the Sun may increase by 0.2% over the next 5 billion years, “this retardation corresponds to a 0.4% decrease in solar energy hitting Earth’s surface,” he said. “This is relatively small compared to the typical changes in the Sun’s brightness caused by Earth’s elliptical orbit, so it’s nothing to worry about.”
related: What is the maximum number of planets that can orbit the Sun?
Of greatest concern is that “as the Sun evolves over the next 5 billion years, stellar evolution models predict that it will increase in brightness by about 6% every 1 billion years, gradually reducing Earth’s magnitude.” Temperature And boiling the oceans,” DiGiorgio said. “That would make Earth uninhabitable to humans, unless the Sun potentially swallows it up.”
evil influence
Recent work suggests orbits of Jupiter and other planets The Solar System have changed over time. So could their orbits be so unstable as to one day affect Earth’s orbit, causing it to be closer to or farther from the Sun? Or maybe some other rogue body passed close enough to the solar system to have a similar effect?
DiGiorgio said, “The problem with trying to predict the gravitational interactions of many-body systems, such as the Solar System or nearby stars, is that they are chaotic, which means they are impossible to predict with any certainty. ” “We have no idea whether, specifically, the planets will be on timescales longer than about 100 million years because small errors in measurement and disturbances from unmodelled interactions become very large over time.”
Still, “we can use this chaos to our advantage by running multiple simulations of the same chaotic system to see how likely an event is to occur,” DiGiorgio said. This is similar to how predictive weather models work, he said.
A 2009 study in the journal Nature (opens in new tab) Of those who did about 2,500 simulations of the Solar System, in about 1%, wedits orbit became unstable, causing it to either crash into the Sun or Venus, “So it is theoretically possible that Mercury moves past Earth and changes its orbit substantially, as was done for Mars in a simulation,” DiGiorgio said. “However, this is very unlikely, as seen by its rarity in their simulations.”
DiGiorgio said it is also very unlikely that a passing star, planet or other body could disturb Earth’s orbit. “My previous envelope calculations say that we should only expect a star to come closer than Pluto’s orbit, which happens once every trillion years,” DiGiorgio said. “any comet Our solar system would not already have enough mass or energy to affect our orbit.”
death of sun
In about 5 billion years, after the Sun’s hydrogen fuel is exhausted, it will begin to swell, becoming a red giant star. Assuming that the Earth continued on its course, would it have been far enough from the dying sun to escape the throes of our star’s death?
DiGiorgio said there is currently some disagreement over how much the Sun will swell during its red giant phase. There is a chance that this will not be enough to reach Earth, which means that our planet could survive and continue in orbit. However, most projections suggest that the Sun will evolve enough to swallow Earth, causing the planet to spiral “inward toward oblivion,” DiGiorgio said.
“However, even if the Earth survives, there is no chance that humans will be able to survive with it,” DiGiorgio said. “The heat and radiation The encroaching Sun would not only boil over the oceans and atmosphere, but it would probably boil off the Earth itself. The flaming lava ball must be released long before humans can swallow it.”
If humans are about 5 billion years from now and want Earth to remain habitable during the Sun’s expansion, we’ll have to slowly move the planet around outward orbit saturnKeeping it temperate enough for life as we know it as the Sun continues to produce more and more energy.
“It’s very impractical, though,” DiGiorgio said. “The simple solution would be to leave Earth and find another planet or solar system to live in.”
Originally published on Live Science.
