The Sun moves in predictable ways through the sky, so you might never think that your relationship with the Earth is constantly changing. In fact, the average distance between the Earth and the Sun varies from year to year.so do we know earth Are you getting closer or farther away from the Sun? And what forces are at work on our planet and our star to make this happen?
in short, Sun It is moving away from Earth over time. On average, the 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. Slightly oval, or oval. This means that the distance from the Sun to Earth ranges from about 91.4 million to 94.5 million miles (147.1 million to 152.1 million km). NASA (opens in new tab) Say.
Yet, on average, the spread between the Earth and the Sun is expanding slowly over time. This increasing distance has two main causes. One is that the Sun is losing mass. Another is cause a tide on earth.
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the sun shrinks
of Nuclear fusion The reaction that powers the sun that converts mass into energy, according to Einstein’s famous formula E = mc^2As the sun is constantly producing energy, its mass is also steadily declining. Over the course of the Sun’s remaining life span—he is estimated to be around 5 billion years. 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 it begins to die, says Brian, an astronomer at the University of California, Santa Cruz. DiGiorgio told Live Science in an email.
0.1% may not sound like much, but “that’s a lot of mass,” says DiGiorgio. “It’s about the same amount of mass as JupiterJupiter, on the other hand, has about 318 times the mass of Earth. Exploratorium (opens in new tab) in California.
The strength of an object’s gravitational pull is proportional to its mass. As the sun loses mass, its gravitational pull on Earth weakens, and the Earth is displaced from its star by about 2.36 inches (6 centimeters) each year, DiGiorgio said. But we shouldn’t throw a bon voyage party into the sun just yet.
“This is fairly negligible compared to the normal variation in Earth’s orbital distance of about 3%, which occurs due to the slightly elliptical orbit,” said DiGiorgio.
the same as MoonThe gravitational pull of causes the tides on the earth, and so do the tides of the earth. gravity pull the sun This stretches the side of the sun facing the Earth, resulting in “tide ebb and flow,” said Britt Scheringhausen, associate professor of physics and astronomy at Beloit University in Wisconsin, at Cornell University. wrote for ask an astronomer (opens in new tab) page.
The sun rotates in about 27 days, According to NASA (opens in new tab)This is faster than the approximately 365 days it takes for the Earth to make one full orbit around the Sun, so the tidal bulge that the Earth produces at the Sun precedes it. The bulge’s mass has an associated gravitational pull that pulls the Earth forward in orbit and away from the Sun, Scheringhausen noted. (A similar effect precedes Earth’s moon slowly moves away from earth (opens in new tab).)
However, the influence of these tidal forces on the Earth’s orbit is very weak, DiGiorgio calculates that the Earth moves about 0.0001 inch (0.0003 cm) away from the Sun each year.
Are there any big changes in the climate?
Could Earth’s increasing distance from the Sun affect Earth’s climate?
“The sun’s light gets darker as the Earth moves away from the Sun,” DiGiorgio said. Given that the distance between the Earth and the Sun could increase by 0.2% over the next five billion years, “this dimming corresponds to a 0.4% reduction in the amount of solar energy hitting the Earth’s surface,” he said. “This is relatively small compared to the normal variations in the Sun’s brightness caused by the Earth’s elliptical orbit, so it’s not too much of a concern.”
“The bigger thing to worry about is that as the Sun evolves over the next 5 billion years, stellar evolution models predict an increase in brightness of about 6% per billion years, and a slow increase in Earth’s brightness. that’s what I’m predicting. temperature “This will render the Earth uninhabitable long before the Sun engulfs it,” DiGiorgio said.
Recent research suggests orbits of Jupiter and other planets solar system changed over time. So could their orbits become destabilized and one day affect the Earth’s orbit, moving it closer or further away from the Sun? could have a similar effect?
“The problem with trying to predict the gravitational interactions of many bodies, like our solar system and nearby stars, is that they are chaotic, which means it’s impossible to predict them reliably,” said DiGiorgio. said. “Specifically, we don’t know where planets will be on timescales longer than about 100 million years, because small errors and perturbations in measurements from unmodeled interactions become too large over time. ”
Still, “we can use this chaos to our advantage by running many simulations of the same chaotic system to see the probabilities of events occurring,” says DiGiorgio. This is similar to how predictive weather models work, he noted.
A 2009 study published in the journal Nature (opens in new tab) In about 1% of about 2,500 simulations of the solar system, Mercuryorbit became unstable and collided with the sun or the sun. Venus“Thus, it is theoretically possible for Mercury to move by Earth and change its orbit significantly, as one simulation did to Mars,” DiGiorgio said. “But given its rarity in their simulations, this is highly unlikely.”
It’s also highly unlikely that a passing star, planet, or other celestial body would disturb Earth’s orbit, DiGiorgio said. “My back-of-the-envelope calculations say that the only time a star is expected to be closer than Pluto’s orbit is about once every trillion years,” DiGiorgio said. “Any Comet Already existing in the solar system, they do not have enough mass or energy to significantly affect their orbits. ”
death of the sun
About 5 billion years after the Sun runs out of hydrogen fuel, it will begin to expand and become a red giant. Assuming the Earth continues its uninterrupted voyage, will it be far enough from the dying Sun to survive the star’s death throes?
DiGiorgio said there is currently disagreement about how much the Sun will swell during the red giant stage. It may not inflate enough to reach the earth. That means our planet could survive and continue orbiting. However, most estimates suggest that the Sun will grow enough to engulf the Earth, leading the planet to spiral “inwards toward oblivion.”
“But even if the Earth survived, there is no chance that humans could live with it,” DiGiorgio said. “Heat and radiation Heat from the approaching Sun will not only boil the oceans and atmosphere, but possibly the Earth itself. Humans must move away from the burning lava ball before it is swallowed. ”
About five billion years from now, if we hope that the Earth will remain habitable during the expansion of the Sun, we will have to slowly move it around its outer orbit. Saturnas we know it, kept it hot enough for life as the sun continued to output more and more energy.
“But this is pretty unrealistic,” said DiGiorgio. “The easier solution is to abandon Earth and live on another planet or solar system.”
Originally published in Live Science.
Is the Earth moving toward or away from the Sun?
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