An artist's concept of our solar system showing a sense of scale and distance.
  • Planets careen around the sun faster than a bullet, and there's a reason for that speed.
  • The closer an object is to the sun, the faster it must move to avoid falling into our star.
  • Planetary scientist James O'Donoghue made two animations to illustrate how this works.
  • For more stories go to www.BusinessInsider.co.za.

At this very moment, Earth and all other planets in our solar system are careening around the sun at unfathomable speeds.

Planetary scientist James O'Donoghue is on a mission to help people visualise that mind-boggling movement. O'Donoghue, who works for the Japan Aerospace Exploration Agency, uses his free time to boil down the complex physics of our solar system into bite-sized animations.

Two of his videos capture how fast each planet travels. The visualisations reveal that planets close to the sun are shooting through space at astonishing speeds. By comparison, the more distant planets seem to meander along at a leisurely pace.

That's because objects closer to the sun have to move faster so that its gravity doesn't pull them into a fiery death.

"All objects that we see in stable orbits around the sun are there because they orbit fast enough to escape its gravitational pull. If they were not fast enough they wouldn't escape," O'Donoghue told Insider. "In short, the planets we see today are the survivors."

The first video, below, shows each planet's velocity on its path around the sun. Mercury, the closest to the sun, travels nearly 48 kilometres per second along its path. Neptune may look slow, but it's still covering 5 kilometres every second. That's about six times faster than a bullet.

The animation above does not show how many orbits the planets are completing relative to each other, though.

So O'Donoghue made another animation, below, to count orbits (note the "number of orbits" ticker that appears to the right of the planets). Each time a planet crosses the screen, it's completing one orbit around the sun.

"Objects close to the sun necessarily orbit faster by virtue of existing there," O'Donoghue said.

As a result, Mercury orbits the sun several times in each Earth year. Neptune, however, takes nearly 164 Earth years to complete its trip around our star.

Pluto is not pictured because it's a dwarf planet.

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