Neptune at Opposition

Neptune at Opposition

Hurricane season is roaring toward its peak about now. But even the biggest hurricanes are tiny compared to storms on some other planets. Late last year, for example, astronomers discovered a storm on Neptune that’s almost wide enough to swallow Earth.

It’s known as a “great dark spot.” Not the spot, but a spot. That’s because it’s not the first one astronomers have seen.

The first was discovered by Voyager 2. It flew past Neptune in 1989 — and it’s still the only craft ever to visit the planet. It found what was dubbed the Great Dark Spot. It was as wide as our entire planet. When Hubble Space Telescope took its first look at Neptune five years later, though, the spot was gone.

The new dark spot isn’t quite as big. But Hubble may have seen its birth over the last few years. Beginning in 2015, it photographed a blob of bright clouds at the same latitudes where the dark spot showed up last year. Those clouds may build at high altitudes while the dark spot is taking shape lower in the atmosphere.

That could mean that it takes a few years to make a dark spot. The spot then vanishes after a few years more, leaving Neptune spotless — until the next one comes along a few years later.

And Neptune is putting on its best showing of the year. It will line up opposite the Sun next week, so it rises at sunset and is in view all night. It’s brightest for the year, too. But you still need some help to spot it, near the western edge of Aquarius.

Script by Damond Benningfield

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