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
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The Moon will pass in front of Neptune, creating a lunar occultation visible from Africa and eastern Brazil. 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.

The occultation will be visible from Fairfield. It will begin with the disappearance of Neptune behind the Moon at 17:03 EDT, though in daylight and at a low altitude of only -2.2 degrees, in the south-eastern sky. Its reappearance will be visible at 17:37 EDT, though in daylight and at a low altitude of 3.3 degrees.

Extreme caution is necessary when pointing binoculars or telescopes at the sky when the Sun is above the horizon, as even a momentary glance at the Sun through such an instrument can cause permanent blindness.

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)
Sudan 23:40–00:52
Democratic Republic of the Congo 23:41–00:50
Chad 23:29–00:52
Libya 23:36–00:46
Niger 23:05–00:44
Mali 22:26–00:28
Nigeria 23:07–00:47
Mauritania 22:15–00:05
Central African Republic 23:32–00:52
Algeria 23:19–00:22
Cameroon 23:21–00:49
Brazil 21:19–22:57
Republic of the Congo 23:33–00:48
Ivory Coast 22:33–00:28
Burkina Faso 22:45–00:32
Gabon 23:26–00:46
Guinea 22:11–00:14
Ghana 22:50–00:35
Egypt 23:42–00:44
Senegal 22:07–23:56
Uganda 23:59–00:45
Benin 23:03–00:37
Liberia 22:23–00:18
Angola 23:42–00:34
Sierra Leone 22:16–00:08
Togo 23:01–00:36
Guinea-Bissau 22:07–23:51
Equatorial Guinea 23:22–00:45
Western Sahara 22:32–23:04
Gambia 22:08–23:46
Cape Verde 21:38–23:12
Ethiopia 23:54–00:43
Rwanda 00:15–00:30
Tanzania 00:15–00:29
Sao Tome and Principe 23:19–00:42
Saint Helena 22:28–23:54

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.

At the time of the occultation, the Moon will be 6 days past new moon and will be 86% illuminated. Neptune will disappear behind the illuminated side of the Moon and reappear from behind the illuminated side of the Moon.

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

Object Right Ascension Declination Constellation Magnitude Angular Size
Neptune 17h37m40s 22°02'S Ophiuchus 7.9 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
15 May 1976 04 Jul 1982 Occultations of Neptune 28 Aug 1982 17 Jun 1992
01 Nov 1980 18 Jul 1982 Occultations 28 Aug 1982 19 Nov 1982

The sky on 16 Aug 2024

The sky on 16 August 2024
Sunrise
06:01
Sunset
19:49
Twilight ends
21:33
Twilight begins
04:17

12-day old moon
Waxing Gibbous

87%

12 days old

Planets
Rise Culm. Set
Mercury 06:36 13:06 19:35
Venus 07:43 14:13 20:43
Moon 18:09 22:31 02:57
Mars 00:49 08:17 15:46
Jupiter 00:47 08:13 15:40
Saturn 20:50 02:29 08:07
All times shown in EDT.

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

17 Jun 1982  –  Neptune at opposition
05 Sep 1982  –  Neptune ends retrograde motion
31 Mar 1983  –  Neptune enters retrograde motion
19 Jun 1983  –  Neptune at opposition

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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