Neptune is the fourth largest planet in the solar system, with a radius of 15,599.4 miles (24,622 kilometers) — the distance between its core and the surface.

"In fact," they added, "Mercury is even the closest planet to Neptune." The commentary is published in Physics Today . An earlier version of this article was published in August 2023.

New images from the space-based observatory offer a novel view of the planet in infrared. By Jonathan O’Callaghan No spacecraft has visited Neptune since 1989, when the NASA probe Voyager 2 flew ...

With its vanishing clouds and now a large dark spot, the planet Neptune appears to be going through some things. Here’s a bit about why the eighth planet in our solar system is causing all this ...

Neptune, long believed to be dark blue, is actually very pale like Uranus, scientists say. They used modern telescopes to re-assess artificially enhanced images taken by NASA's Voyager 2 probe.

Since then, the planet has only been visited once by spacecraft when, in 1989, Voyager 2 completed its 'Grand Tour' of our solar system's outermost planets. It took this image of Neptune and its moon ...

In 1989, Voyager 2 became the first and only spacecraft to ever fly by Neptune, and images from that mission famously show a planet that's a deep azure color. But in reality, Neptune is far more ...

Mysterious planet has "unusually shiny atmosphere" and may contain water vapor, ... This artist's concept depicts the planet GJ 1214 b, a "mini-Neptune" with what is likely a steamy, hazy atmosphere.

Astronomers pointed the James Webb Space Telescope at a common kind of planet that's bigger than Earth but smaller than Neptune. What they saw wasn't what they expected.