Neptune

Neptune tonight from your location

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This panel computes tonight's position and rise and set times for Neptune in your browser, and it needs JavaScript to run. The rest of this page, including the month-by-month table below, is fully readable without it. For a live all-sky view, open the Sky Map or Today in the Sky.

Everything is computed on your device. Tapping "Use my location" sends your coordinates once to a place-name service only to show your city's name. Times appear in your device's time zone.

Neptune at a glance

Physical data: NASA NSSDCA Neptune Fact Sheet.

Where is Neptune month by month?

The table below tracks Neptune through the next twelve months: the constellation it sits in on the 15th of each month (dates in Universal Time), whether it is a morning object, an evening object or up all night, and how bright it looks.

How to see Neptune

Neptune never becomes bright enough for the naked eye; no ancient culture ever recorded it. Astronomers grade brightness on the magnitude scale, where lower numbers mean brighter objects. At its very best, around opposition (the point in the year when Earth passes between Neptune and the Sun and the planet is closest), it reaches magnitude 7.67, still below what an unaided eye can detect even under a perfect dark sky.

Binoculars bridge the gap easily. From a reasonably dark spot, any ordinary pair will pull Neptune in, but it looks like nothing more than a faint bluish star, so the real work is identification: know which field it sits in tonight, star-hop there, and pick out the one point that does not belong on the chart.

A telescope is where Neptune finally gives itself away. Push the magnification as high as the night's steady air allows and the star-like point resolves into a tiny, even, blue-gray disk, about 2.3 arcseconds across at opposition (an arcsecond is 1/3600 of a degree), the smallest disk any planet shows us. Do not expect surface detail; at this distance you are only confirming a disk. Stars stay sharp points and twinkle, while Neptune holds a calm, rounded softness with a distinctly cool tint. Return a week later and the "star" will have crept against its neighbors.

The color is easy to misjudge, too. The deep azure in famous Voyager 2 portraits is a close-range spacecraft view; at the eyepiece the tint is a muted blue-gray. That serene shade hides the fiercest weather in the solar system, with winds measured at up to 580 meters per second, around 1,300 miles per hour.

Neptune's cycles

Neptune's defining rhythm is sheer slowness. One trip around the Sun takes 164.79 years, so the planet creeps only about 2 degrees eastward against the stars each year; it spends years crossing a single constellation, and a whole human lifetime covers barely half of its single trip around the sky. Watch it on the Sky Map and it looks nailed in place from month to month; only the slow year-over-year drift betrays it as a wanderer.

That slowness sets the pace of the observing calendar. Neptune's synodic period, the time from one opposition to the next, is 367.49 days, barely more than a calendar year: Earth laps a target that has hardly moved, so each opposition falls just two or three days later than the last. The synodic vs sidereal lesson explains why those two clocks differ, and the weeks around opposition are the time to run your gear through the Telescope Calculator and see what magnification a 2.3-arcsecond disk demands.

Farther out, Neptune is tied to something stranger still. It is locked in a true 3:2 orbital resonance with Pluto: Neptune completes three orbits in the time Pluto completes two. Pluto's stretched path even brings it closer to the Sun than Neptune for part of each circuit, yet the resonance choreographs their motion so that they are never near the crossing region at the same time. They can never collide. Gravity itself governs the timing, and that is what a true resonance means.

No two planets meet less often. A conjunction of Uranus and Neptune, the two outermost giants passing each other in our sky, comes around less than once in a typical human lifetime. Fittingly, Uranus is the planet whose wanderings gave Neptune away in the first place.

To see where these periods fit among everything else that repeats overhead, find the Neptune synodic period in the full list, sorted by length, on the Cycles page.

What's next for Neptune

Over the next few years, Neptune's calendar comes down to two kinds of event: the oppositions worth circling, and the solar conjunctions that hide it behind the Sun for a few weeks. Computed with the same engine that runs this site's live sky tools; dates are in Universal Time.

Frequently asked questions

How was Neptune discovered?

By mathematics first. Uranus kept straying from its computed orbit, and John Couch Adams and Urbain Le Verrier independently worked out that the gravity of an unknown planet farther out could explain the drift. Le Verrier sent his predicted position to the Berlin Observatory, and on the night of September 23, 1846, Johann Galle found Neptune within about a degree of that prediction.

Can you see Neptune without a telescope?

Not with the naked eye. Neptune peaks at magnitude 7.67 (lower magnitude numbers mean brighter), which is below what an unaided eye can reach even under a very dark sky. Ordinary binoculars will show it from a dark site, but only as a faint star-like point, so you need a chart of its current position to know which point is the planet.

Why is Neptune blue?

Its atmosphere is mostly hydrogen and helium with about 1.5 percent methane, and methane absorbs the red part of sunlight while the blue part scatters back into space, so the planet reflects a blue tone. Through an amateur telescope the color is a subtle blue-gray; the deep azure in famous spacecraft images is the same methane effect, boosted by close range and image processing.

How long is a day and a year on Neptune?

Neptune spins fast for its size: one rotation takes about 16.1 hours, so its day is far shorter than Earth's. Its year is enormous: one full orbit of the Sun takes 164.79 Earth years, which means Neptune has completed only one orbit since its discovery in 1846.

Will Neptune and Pluto ever collide?

No. Pluto's stretched orbit does bring it closer to the Sun than Neptune for part of each circuit, but the two are locked in a 3:2 orbital resonance: Neptune completes three orbits in the time Pluto completes two. That repeating rhythm always keeps them far apart whenever their paths come near each other, so a collision cannot happen.

When is the next Neptune opposition?

Neptune reaches opposition on September 26, 2026. At opposition Earth passes directly between Neptune and the Sun, so it rises around sunset, stays visible all night, and is at its closest and brightest for the year, about magnitude +7.8 in Pisces.

Keep exploring

• Sky Map: star-hop to Neptune's exact field from your location tonight
• Telescope Calculator: what your scope can make of a 2.3-arcsecond disk
• Uranus: the drifting planet that gave Neptune away, and an easier first target
• Pluto: Neptune's 3:2 resonance partner, forever kept out of reach
• Synodic vs Sidereal lesson: why Neptune's opposition slips only two or three days a year