What is a black moon? How and when to watch the rare lunar event as it appears in the sky TONIGHT
Tonight, a rare lunar phenomenon called the “black moon” will occur, giving stargazers a unique view of the night sky.
This unusual astronomical event, which occurs only once every 29 months, has fascinated people for centuries.
A black moon is simply the second new moon in the span of a calendar month – the first moon phase with the shadow side of the moon pointing towards us.
Because it is a new moon, the black moon cannot be seen, even with a telescope.
But it should provide excellent stargazing opportunities after sunset and into the wee hours of Tuesday.
The moon will be conspicuous by its absence from the night sky, as if blotted out by the gods, while the stars and planets will appear especially bright.
Top tips for stargazers include choosing a spot with a wide and unobstructed view of the sky, away from artificial lights such as street lamps.
You won’t want to miss it because the last black moon was in April 2022, while the next one after tonight won’t be until August 2027.
A new moon occurs when our natural satellite has 0 percent illumination, making the moon’s disk invisible to the naked eye (file photo)
The reason for a black moon, as it is commonly called by amateur astronomers and space enthusiasts alike, is quite simple.
Over 29.5 days, the moon goes from a new moon (with 0 percent illumination as seen from Earth) to a full moon (100 percent illumination) and back again.
Because the lunar cycle (29.5 days) is shorter than the months of the year, there are sometimes two new moons in a month instead of just one.
When this happens, people call the second new moon of the month the black moon – an event that some astrologers interpret as spiritually significant.
But aside from the fact that it’s a new moon, scientists don’t often view the black moon as a meaningful event.
“A black moon is just a second new moon that occurs in one calendar month,” says Walter Freeman, an associate professor of physics at Syracuse University.
‘If a new moon occurs at the beginning of a calendar month, the next one will occur before it is over.
“From a scientific perspective, this is no different than any other new moon.”
During the 29.5-day lunar cycle, we observe a new moon (with 0 percent illumination), a waxing moon (when the amount of illumination on the moon increases), a full moon (100 percent illumination), and then a waning moon. moon (when the visible surface becomes smaller)
Images show the new moon, waxing moon, full moon and waning moon as they appear during the 29.5-day lunar cycle
The first new moon of this month occurred on December 1, while the second new moon of December (the black moon) is December 30.
According to the US Naval Observatory, this will take place on December 30 at 22:27 GMT (17:27 EDT).
This marks the precise astronomical moment when the moon comes exactly between the Earth and the sun, while the side of the moon that is in shadow faces the Earth.
According to Professor Freeman, there is ‘nothing to see’ when it comes to the moon itself, but the lack of moonlight creates ideal conditions for stargazing, making it easier to spot constellations such as Orion, Taurus and Leo.
It will also be easier to see planets like Venus – the brightest thing in the sky with a very subtle yellow tint.
Mars should also be visible as a reddish dot, near the constellation Cancer the Crab.
The public does not need a telescope to view the planets, which are best seen when there are clear skies without clouds.
In a sky full of stars, the planets can be identified by their distinct lack of sparkle.
Tonight, the lack of moonlight due to the new moon creates ideal conditions for stargazing. Mars should also be visible as a reddish dot, near the constellation Cancer the Crab (left)
Stars twinkle, while planets usually shine steadily.
For the best vision, find a spot away from sources of light pollution such as street lights, and give your eyes enough time to adjust to the darkness.
However, the Met Office is warning of ‘generally cloudy conditions’ this evening which could affect visibility.
In London and the South East the minimum temperature will be 7°C tonight, so it’s a good chance to look at the sky without it getting too cold.
If you miss the black moon, you can see the ‘blue moon’ (the second full moon in a calendar month) sooner, although it won’t appear until 2026.
Likewise, this rare astronomical event normally occurs about every two or three years – hence the expression ‘once in a blue moon’.
While the next black moon won’t occur until August 2027, the next blue moon will be in May 2026.
Meanwhile, there will be two ‘supermoons’ in 2025 – when the full moon appears bigger and brighter than normal.
According to Royal Museums Greenwich, the supermoons will arrive on November 5 and December 4, 2025.