The Solar System Is Even More Massive Than You Think

Our solar system got a little smaller when planethood was yanked out from underneath Pluto and it was demoted to a dwarf planet. But that’s only if your definition of a solar system is limited to the number of planets orbiting a star.

As NASA’s Goddard Space Flight Center points out in a new video, the size of our solar system depends on how you are observing it. If you go by the distance of the farthest planet, Neptune lies almost 3 billion miles away from the sun.

How does that compare to other solar systems around the universe? We can only go by the stars and planets that we have identified and discovered, and out of those it would only be reasonable to compare our solar system to those with a similar number of planets. In the Trappist-1 system that was recently discovered and which scientists introduced to the public earlier this year, there are seven rocky planets closely orbiting a dwarf star — compared to our system’s eight planets (sorry again, Pluto lovers) orbiting a star about 12 times more massive than that dwarf. The outermost planet in that alien system, Trappist-1h, is about 6 million miles away from its star, according to recent NASA estimates.

That is significantly closer in than Neptune, at its almost 3 billion mile distance from the sun. However, scientists have noted that it’s possible there are more planets in the Trappist-1 system that have yet to be discovered.

To be fair, astronomers also suggest there might be two more planets in our own system, a ninth and 10th planet, that have yet to be discovered, potentially extending the size of our neighborhood.

But there is more to a solar system than just planets. Beyond Neptune, for example, there is a ring of icy material called the Kuiper belt that includes Pluto and other dwarf planets as well as comets.

And as NASA points out in its video, the sun’s magnetic fields reach as far as 10 billion miles.

That distance is so far that in humanity’s decades of space exploration, only two spacecraft have gone beyond its reach — and it was relatively recently.

NASA is celebrating 40 years since the Voyager 1 and Voyager 2 spacecraft were launched in 1977. The space agency’s Jet Propulsion Laboratory keeps a running count of how many miles the spacecraft have traveled across space. As of the 40th anniversary on Sept. 5, Voyager 1 was 12.98 billion miles from the sun and Voyager 2 was more than 10.7 billion miles, putting them both right outside the sphere of influence of the sun’s magnetic fields.

They still have not cleared all the material in our stellar neighborhood, however. Farther out than the Kuiper Belt and the heliosphere is a much larger icy group of material called the Oort Cloud, which can extend as far as 9.3 trillion miles away from the system center.

And if you instead measure the size of the solar system by the places at which objects would be affected by the sun’s gravity, the maximum distance becomes between 4 trillion and 20 trillion miles away from the sun, according to NASA.

“Like everything in exploration, it depends on how far you’re willing to go,” according to the video.