The Moon in conjunction with Venus and Jupiter, with the Very Large Telescope in the foreground. Image © Y. Beletsky, ESO, 2009.

Lunar occultation of Neptune

Dominic Ford, Editor
From the Lunar Occultations feed

Objects: Neptune

The Moon will pass in front of Neptune, creating a lunar occultation visible from southern Argentina, southern Chile, Antarctica and western Falkland Islands. Although the occultation will only be visible across part of the world – because the Moon is so close to the Earth that its position in the sky varies by as much as two degrees across the world – a close conjunction between the pair will be more widely visible.

Unfortunately the occultation will not be visible from Fairfield.

The map below shows the visibility of the occultation across the world. Separate contours show where the disappearance of Neptune is visible (shown in red), and where its reappearance is visible (shown in blue). Solid contours show where each event is likely to be visible through binoculars at a reasonable altitude in the sky. Dotted contours indicate where each event occurs above the horizon, but may not be visible due to the sky being too bright or the Moon being very close to the horizon.

Map showing where the occultation is visible

Outside the contours, the Moon will not pass in front of Neptune at any time, or is below the horizon at the time of the occultation. However, a close conjunction between the pair will be visible across much of the world.

The map can be downloaded in PNG , PDF or SVG format. A KMZ file , is also available, which can be opened in Google Earth to provide a higher resolution map.

The animation below shows the path of the occultation across the Earth's globe. The red circle shows where the Moon appears in front of Neptune.

You can download this video in MP4 or OGG format.

A complete list of the countries and territories where the occultation will be visible is as follows:

Country Time span
(UTC)
Argentina 08:03–09:13
Chile 08:01–09:14
Antarctica 08:22–09:24
Falkland Islands 08:14–09:10

Lunar occultations are only ever visible from a small fraction of the Earth's surface. Since the Moon is much closer to the Earth than other celestial objects, its exact position in the sky differs depending on your exact location on Earth due to its large parallax. The position of the Moon as seen from two points on opposite sides of the Earth varies by up to two degrees, or four times the diameter of the full moon.

This means that if the Moon is aligned to pass in front of a particular object for an observer on one side of the Earth, it will appear up to two degrees away from that object on the other side of the Earth.

The position of Neptune at the moment of the occultation will be as follows:

Object Right Ascension Declination Constellation Magnitude Angular Size
Neptune 20h33m50s 18°31'S Capricornus 8.0 0'02"

The coordinates above are given in J2000.0.

Next/previous occultations

« Previous Next »
Visible from the Contiguous United States Worldwide Worldwide Visible from the Contiguous United States
28 Jul 1999 02 Mar 2000 Occultations of Neptune 26 Apr 2000 23 Jun 2008
19 Oct 1999 04 Mar 2000 Occultations 31 Mar 2000 01 Aug 2000

The sky on 18 May 2024

The sky on 18 May 2024
Sunrise
05:29
Sunset
20:07
Twilight ends
22:03
Twilight begins
03:33

10-day old moon
Waxing Gibbous

80%

10 days old

Planets
Rise Culm. Set
Mercury 04:37 11:15 17:53
Venus 05:21 12:29 19:38
Moon 15:23 21:31 03:28
Mars 03:39 09:57 16:15
Jupiter 05:35 12:49 20:02
Saturn 02:43 08:23 14:03
All times shown in EDT.

Warning

Never attempt to point a pair of binoculars or a telescope at an object close to the Sun. Doing so may result in immediate and permanent blindness.

Source

The circumstances of this event were computed using the DE430 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).

This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.

Related news

13 Oct 1999  –  Neptune ends retrograde motion
08 May 2000  –  Neptune enters retrograde motion
27 Jul 2000  –  Neptune at opposition
15 Oct 2000  –  Neptune ends retrograde motion

Image credit

The Moon in conjunction with Venus and Jupiter, with the Very Large Telescope in the foreground. Image © Y. Beletsky, ESO, 2009.

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