Dennis Mammana: How to find Neptune after dark | Outside


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Finding Neptune among the faint stars of Aquarius isn’t easy, and since this distant world is invisible to the naked eye, you’ll need to use “star hopping” techniques and have very dark rural skies, binoculars, and a lot of patience to find it. (

Do you remember a few years ago when Pluto was considered no longer a planet? The internet erupted in protests.

“Why isn’t Pluto a planet? people cried. “It was a planet when I went to school and, as far as I’m concerned, it still is!”

Well, scientists have the job of classifying everything, and when new data or knowledge becomes available, they have to reclassify objects to better fit the pattern.

So it shouldn’t have surprised anyone who follows science that astronomers reclassified Pluto, a small ball of ice near the edge of our planetary system, as a “dwarf planet.”

And that means Pluto’s reclassification from the official planet gives the honor of being the furthest planet from the sun to Neptune.

Neptune was discovered after astronomers learned that the planet Uranus, which William Herschel had discovered 6½ decades earlier, was not tracking the precise path skywatchers had expected.

A young English astronomer named John Couch Adams calculated that the movement of Uranus was apparently affected by another world that lay beyond and that its gravitation pulled on it. He even calculated where this unknown planet was; unfortunately no one in England ever bothered to look for him.

It was the same in France where Urbain Le Verrier independently made the same calculations. Again, no one seemed to care.

But Le Verrier did not give up. He showed his calculations to German astronomer Johann Galle, who pointed his telescope skyward and found the new planet – eventually named Neptune – on his very first night of searching!

That was in 1846, and since then few beginning astronomers have even sought out this distant world.

Well, now is a good time to change that because, this week, Neptune reaches its point of opposition where it not only sits closest to Earth – about 2.69 billion miles away – but also shines at its maximum.

However, finding Neptune among the faint stars of Aquarius is not easy, and since this distant world is invisible to the naked eye, you will need to use “star hopping” techniques and have very dark rural skies, binoculars and lots of patience to spot it.

First, find the bright Jupiter in the eastern sky, and the dim star Phi Aquarii in the west; this star forms a nice little “arrow” that aims perpendicular to Jupiter. Aim your binoculars about two-thirds the distance between Jupiter and Phi.

There, you might spot Neptune as a pale bluish “star.” A small telescope pointed in this direction will show a distinctive bluish-green tint that sets it apart from nearby stars.

If you’re not sure you’ve found it, draw the area, taking care to mark each star in its exact position. Then, a week or two later, examine that same region of the sky and see which of the faint objects has changed position. It’s Neptune!

If needed, you can click here for a more detailed research table for the planet.

As difficult as Neptune can be to find, there is something truly special about seeing the outermost planet in our solar system with our own eyes!

— Dennis Mammana is an astronomy writer, author, speaker, and photographer working under the clear, dark skies of the Anza-Borrego Desert in outback San Diego County. Contact him at [email protected] and connect with him on Facebook: @dennismammana. Click here to read previous columns. The opinions expressed are his own.


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