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Welcome to HMNAO's Moon Watch web site.
Have you ever wondered at what stage you can see the new crescent moon?

The next new moon will occur on Saturday March 17th 2018 at 13:12 GMT/UT marking the start of lunation 1178.

The timing of March's new moon means that sightings of the new crescent Moon on Saturday March 17th are possible for observers with conventional amateur-sized telescopes based in the Pacific Ocean region between the International Date Line and French Polynesia. Observers to the west of the International Date Line may be able to make telescopic observations of Sunday March 18th. Naked-eye sigthings under excellent conditions may be possible the same day from the Solomon Islands, New Guinea, northern and western Australia, the Philippines, most of Indonesia and most of China except the north-east. Easy sightings of the crescent moon should be possible from western Indonesia and Malaysia, India, the Arabian Peninsula, the Middle East, Africa, Europe except the north-east and Scandinavia, the southern half of the British Isles and the Americas on Sunday March 18th. The crescent moon should be visible globally on Monday March 19th. We would therefore ask observers to make their sightings of the new crescent Moon between March 17th and March 19th and report them to us.

If you go out just after sunset over the three or four days following the instant of new moon and have a look low in the western half of the sky near where the Sun set, you can try and observe the new crescent moon.

You can make the observation with just your eyes or with binoculars or a telescope. Never look at the Sun directly or through binoculars or a telescope as you will damage your eyesight. If you are going to use binoculars or a telescope to find the new crescent moon, you must make sure the Sun has set.

The crescent moon will be faint shortly after new moon but will brighten from night to night as the crescent thickens. Cloud or aircraft vapour trails can easily be mistaken for the Moon so be careful when making the observation.

Scan the western horizon close to where the Sun set. If you can see the Moon, let us know by entering your observation and location in our report form. We need to know the date and time of your observation, what the crescent looked like, where it was in the sky relative to the position on the horizon where the Sun set and something about the weather conditions and you, the observer. Even if the weather is clear and you cannot see the Moon, let us know. A negative observation will also help us!

Come back to this site later in the month and you can find out what you should have seen from your observing site. You can also sign up for an e-mail reminder of the date and time of the next new moon so you can try your observing skills again.

Over time, we will process your observations and try to improve the models we use to predict the first sighting of the new crescent moon. Currently, these predictions produce a classification for a particular date and location ranging from A (crescent easily visible) through to F (crescent impossible to see).

For those groups who use the first sighting of the new crescent moon in their calendars, these predictions are very significant and mark the beginning and end of periods of fasting and festivals. More information on these predictions is available on this site.

This site allows observers to look at the global visibility of the next new moon, to check their observations of the last new moon, to report their observations and to receive/stop e-mail reminders of the next new moon.

Preliminary results will also be reported on the site when they become available.

Further information on the visibility of the new crescent moon for a specific location can be found on our Websurf site by selecting the Crescent Moon Visibility option from the menu.
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An ancient Maya calendar
A satellite dish scanning the sky
What we want you to do
  • Go out each evening following the day of the new moon.
  • Find a westerly facing spot with a clear view of the horizon.
  • Wait for the Sun to set, then look for the crescent moon in that part of the sky.
  • Don't look directly at the Sun, using your naked eye, binoculars or a telescope.
  • Can you see the crescent moon? Are you sure? Is it a cloud or a vapour trail?
  • Make a note of where you were, the date and time of your observation, the weather conditions and whether you saw the Moon or not.
  • Come to this website and report your observation.
  • Try and observe the crescent moon each night until you see it, reporting each observation attempt.
  • Sign up for an e-mail reminder of the next new moon and come back next month and try the same thing again.
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Permission must be granted to reproduce this material. HM Nautical Almanac Office and the UK Hydrographic Office do not accept any responsibility for any loss or damage arising from the use of information contained in the following pages.

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