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

Lunar occultation of Sigma Sagittarii

Dominic Ford, Editor
From the Lunar Occultations feed

Objects: Nunki

The Moon will pass in front of Sigma Sagittarii (Nunki), creating a lunar occultation visible from the Americas.

Unfortunately the occultation will not be visible from Fairfield, though it will be visible from eastern parts of the Contiguous United States anda close conjunction between the pair will be more widely visible.

The map below shows the visibility of the occultation across the world. Separate contours show where the disappearance of Sigma Sagittarii (Nunki) 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 of the contours, the Moon does not pass in front of Sigma Sagittarii (Nunki) at any time, or is below the horizon at the time of the occultation. However, a close conjunction between the pair may be visible.

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.

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

Country Time span
Mexico 17:22–05:17
Colombia 23:00–01:09
Venezuela 23:11–01:09
The Contiguous United States 02:31–08:19
Peru 22:57–15:06
Ecuador 05:16–00:54
Brazil 22:54–22:55
Cuba 18:51–22:54
Nicaragua 11:10–00:17
Guyana 23:15–01:16
Honduras 11:03–04:47
Guatemala 10:54–22:36
Panama 05:36–00:39
Costa Rica 11:22–00:27
Dominican Republic 19:01–00:02
Haiti 19:01–23:58
Bahamas 18:43–23:14
Belize 10:56–22:34
El Salvador 11:06–04:49
Jamaica 19:09–23:49
Puerto Rico 19:03–00:06
Suriname 23:17–01:17
Trinidad and Tobago 23:31–00:03
Guadeloupe 17:28–00:08
Saint Vincent and the Grenadines 23:40–00:06
Turks and Caicos Islands 18:57–23:57
Barbados 23:39–00:06
British Virgin Islands 19:03–00:07
Cayman Islands 19:07–23:37
Martinique 09:50–00:07
Curacao 06:13–00:39
Saint Kitts and Nevis 17:24–00:08
Saint Lucia 23:48–00:07
U.S. Virgin Islands 19:03–00:07
Antigua and Barbuda 17:21–00:09
Dominica 17:36–00:08
Anguilla 17:19–00:08
Bonaire, Saint Eustatius and Saba 17:21–00:35
Grenada 23:38–00:05
Bermuda 18:44–23:32
Montserrat 17:26–00:08
Aruba 06:10–00:37
Sint Maarten 17:20–00:08
Saint Barthelemy 17:20–00:08
Saint Martin 17:19–00:08
Clipperton Island 05:27–12:07
Navassa Island 19:07–23:52

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 Sigma Sagittarii (Nunki) at the moment of the occultation will be as follows:

Object Right Ascension Declination Constellation Magnitude Angular Size
Sigma Sagittarii (Nunki) 18h55m10s 26°17'S Sagittarius 2.1 0'00"

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
25 Jun 2021 22 Jul 2021 Occultations of Sigma Sagittarii (Nunki) 15 Sep 2021 20 Jun 2027
25 Jun 2021 16 Aug 2021 Occultations 12 Sep 2021 03 Nov 2021

The sky on 18 Aug 2021

The sky on 18 August 2021
Twilight ends
Twilight begins

10-day old moon
Waxing Gibbous


10 days old

Rise Culm. Set
Mercury 07:26 13:57 20:29
Venus 09:12 15:14 21:15
Moon 17:21 21:53 02:24
Mars 07:28 13:59 20:30
Jupiter 19:50 01:04 06:19
Saturn 18:53 23:47 04:41
All times shown in EDT.


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.

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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