What would happen if Earth's orbit shifted?

Our planet is an extraordinary place. From the breathtaking beauty of the Grand Canyon and the Great Wall of China to the curious popularity of electronic dance music and that reality show featuring wealthy women from New Jersey, Earth is full of strange and wonderful surprises. And there are countless natural marvels right under our feet that many of us overlook, like the fact that our planet is always orbiting the sun.

Although you might not notice it, Earth is in motion at this very moment. Gravity, not just the title of a Sandra Bullock movie, is a natural force that pulls objects together. It’s Earth’s gravity that keeps everything — from humans to animals to buildings — firmly in place. Likewise, the sun, which is around 100 times larger than Earth, exerts its own gravitational force, pulling all the planets around it. This is why we complete an orbit around the sun each year [sources: NASA, NASA].

A change in Earth’s orbit — perhaps triggered by the sun vanishing or a larger celestial body entering the solar system with a stronger gravitational force — would likely lead to the end of life as we know it.

Without an orbit, Earth would likely plummet straight into the sun. Our planet’s orbit around the sun keeps it from being drawn in by the sun’s gravitational pull. Imagine throwing a tennis ball off a roof. The harder you throw it, the further it travels before gravity pulls it down. Earth moves around the sun at an impressive speed of 18.5 miles (29.8 kilometers) per second. It’s always falling toward the sun but moves fast enough to avoid colliding with it. If the orbit stopped, though, Earth would quickly move closer to the sun, burning up everything as it drew nearer [sources: National Graphic, Bhatia, Dutch].

A slight shift in Earth’s orbit would primarily impact the planet's temperature. The closer we are to the sun, the hotter it gets. Even a minor move toward the sun could trigger significant changes. Warming would cause glaciers to melt, raising sea levels and flooding large portions of the planet. As there would be less land to absorb the sun's heat, temperatures would continue to rise. Higher levels of carbon dioxide and vapors released from the oceans would also contribute to the warming [source: Nevins].

On the other hand, if Earth’s orbit shifted farther from the sun, it would cool down and possibly freeze. Oceans would ice over, leading to less carbon dioxide and vapor being released. This would also lengthen the years, as a greater distance from the sun would slow down the orbit, making it take longer to complete a full revolution around the star [source: Nevins].

A change in Earth's orbit wouldn't just affect our planet; it could have consequences for the entire solar system. Even a slight alteration in Earth’s path could cause collisions between planets. It could also disrupt Earth’s delicate alignment with Jupiter, the largest planet. Jupiter acts as a protective shield, deflecting harmful gases and asteroids that might otherwise strike Earth [source: Howell].