These decades of observations have revealed a lot about the true nature of this mysterious world. Astronomers were able to examine the chemical composition of Neptune, watching the gusts of a huge storm the size of a planet in its atmosphere.
Data from the Voyager 2 flyby also confirmed the presence of a faint ring system and a group of dusty bands known as arcs, which are thought to have been carved and sorted by the gravitational effect of the nearby moon Galatea.
Now, a new image captured by the powerful James Webb Space Telescope has given us the best view of Neptune’s rings since Voyager 2 visited the distant world 30 years ago.
The new image was captured using a near-infrared webcam (NIRCam). In the infrared portion of the light spectrum, Neptune’s rings reveal themselves as a group of well-defined halos circling the ghostly planet, punctuated by an array of diffuse dust bands.
Seven of Neptune’s moons can also be seen dotting the image, including the brilliantly luminous shape of Tritan, which dominates the upper part of the horizon. The largest natural satellite of Neptune travels around the host planet in the opposite direction to the other satellites of the ice giant in what is known as a retrograde orbit.
Scientists believe that Tritan was once a planet that roamed through the Kuiper Belt, a distant icy debris field that surrounds our star. However, at some point in the ancient past, the wanderer was passing near Neptune, and was captured by its powerful gravity.
Nowadays, Triton is encased in a frozen layer of nitrogen, which allows it to reflect about 70 percent of the sunlight hitting its surface. Because of this, he is able to outperform the mighty Neptune, despite being smaller than the Earth’s moon.
The dullness of Neptune shown in the new image is also due to the composition of the atmosphere. Methane in the upper atmosphere is very adept at absorbing red and infrared light from our Sun, and at reflecting other wavelengths. This is why the planet appears blue in visible-light images taken by the Hubble Space Telescope.
However, the same infrared absorption properties make the majority of Neptune’s surface relatively dark in the new JWST image. However, bright clusters of high-altitude clouds and a prominent storm could be seen making their way across the face of the strange world.
A brighter band of infrared light can also be seen near the equator, indicating the region where atmospheric ice clouds fall toward the surface and heat up.
JWST is set to turn its gaze to Neptune again later this year. Be sure to check out IGN’s science page to keep up with the latest and weirdest developments in space exploration.
Anthony Wood is a freelance science writer at IGN