Neptune

Neptune is the eighth and farthest planet from the sun, and it is the fourth-largest planet in the solar system. It has a diameter of 49,244 kilometers and a mass of 1.02 x 10^26 kilograms, making it about 17 times more massive than Earth. Neptune is an ice giant planet, primarily composed of water, methane, and ammonia, and has a deep, turbulent atmosphere with strong winds and large storms, including the famous Great Dark Spot and the smaller Dark Spot. The planet has a day length of approximately 16.1 Earth hours and an orbital period of 165 Earth years. Neptune has 14 known moons, with the largest being Triton, a captured Kuiper Belt object with a highly inclined and retrograde orbit. Neptune also has a faint and dynamic ring system, which was discovered in 1984 during a stellar occultation. The planet has been explored by only one spacecraft, NASA's Voyager 2, which flew by the planet in 1989, providing the most detailed images and data of the planet and its moons to date.

Neptune is currently in the constellation of Pisces.

The current Right Ascension of Neptune is 23h 51m 25s and the Declination is -02° 14’ 44” (topocentric coordinates computed for the selected location: Greenwich, United Kingdom edit_location_alt). The current magnitude of Neptune is 7.78 (JPL).

Today's rise, transit and set times of Neptune from Greenwich, United Kingdom edit_location_alt (all times relative to the local timezone Europe/London):

If you need to access this information frequently for your observations, you can create a simple customized Quick Access page, so that you can easily bookmark it in your browser favorites or add a shortcut to your mobile phones' home screen.

Available Resources

• Position and finder charts (see also Where is Neptune?)
• Distance from Earth (see also How far is Neptune from Earth?)
• When does Neptune rise and set?
• Brightness (see also How bright is Neptune?)
• Physical data. Detailed information about physical properties of Neptune, such as mass and geometric properties.
• 15 days ephemerides. Table showing celestial coordinates and magnitude of Neptune for the past and next 7 days.
• Interactive sky chart. An online planetarium application that shows where to locate Neptune in the sky from your location.
• Live position tracker. A high precision sky chart that uses real deep sky imagery to help locate Neptune with your telescope or on your astrophotographies.

Higher precision deep sky finder chart, 60 arcmin wide, showing where Neptune is right now. Click on the image to see a more detailed fullscreen tracker view.

Also check out Where is Neptune?, a page that provides all the information needed to find Neptune in the sky and additional links to sky charts.

Neptune Distance from Earth

The distance of Neptune from Earth is currently 4,514,203,943 kilometers, equivalent to 30.175590 Astronomical Units. Light takes 4 hours, 10 minutes and 57.7635 seconds to travel from Neptune and arrive to us.

The following chart shows the distance of Neptune from Earth as a function of time. In the chart the distance data is measured in Astronomical Units and sampled with an interval of 1 day.

The value of the reported distance might be somewhat inaccurate around the times of closest approach for objects passing extremely close to Earth. The value of the distance of Neptune from Earth is also available as a real time updated value in the Live Position and Data Tracker.

Closest Approach of Neptune to Earth

Between 1 January 1600 and 30 December 2499, the closest approach of Neptune to Earth happens on Thu Nov 8 2373 at a distance of 28.806366 Astronomical Units, or 4,309,370,997 kilometers:

NOTE: values for the closest approach are computed with a sampling interval of 1 day.

Neptune Brightness and Light Curve

The following chart is the predicted light curve (visual magnitude as a function of time) of Neptune, according to the most recent ephemerides data. Magnitude data is sampled with a 2 days interval and there might be inaccuracies for objects changing brightness very rapidly during the course of a few days. For comets there could be large discrepancies between the observed and predicted brightness because of their highly dynamic behaviour.

Neptune 15 Days Ephemeris

The following table lists the ephemerides of Neptune computed for the past and next 7 days, with a 24 hours interval. Click on each row of the table to locate Neptune in our Online Planetarium at the chosen date.

Date	Right AscensionR.A.	DeclinationDec.	MagnitudeMag	Apparent DiameterDiameter	Constellation
2023 May 26	23h 50m 57s	-02° 17’ 17”	7.79	2.2”	Pisces
2023 May 27	23h 51m 02s	-02° 16’ 53”	7.78	2.2”	Pisces
2023 May 28	23h 51m 06s	-02° 16’ 29”	7.78	2.2”	Pisces
2023 May 29	23h 51m 10s	-02° 16’ 08”	7.78	2.2”	Pisces
2023 May 30	23h 51m 14s	-02° 15’ 46”	7.78	2.2”	Pisces
2023 May 31	23h 51m 18s	-02° 15’ 24”	7.78	2.2”	Pisces
2023 Jun 01	23h 51m 20s	-02° 15’ 03”	7.78	2.2”	Pisces
2023 Jun 02	23h 51m 24s	-02° 14’ 44”	7.78	2.3”	Pisces
2023 Jun 03	23h 51m 28s	-02° 14’ 26”	7.78	2.3”	Pisces
2023 Jun 04	23h 51m 30s	-02° 14’ 08”	7.78	2.3”	Pisces
2023 Jun 05	23h 51m 34s	-02° 13’ 50”	7.77	2.3”	Pisces
2023 Jun 06	23h 51m 38s	-02° 13’ 32”	7.77	2.3”	Pisces
2023 Jun 07	23h 51m 41s	-02° 13’ 17”	7.79	2.3”	Pisces
2023 Jun 08	23h 51m 42s	-02° 13’ 01”	7.79	2.3”	Pisces