Residents of the Americas, most of Europe and West Africa will be able to observe a total lunar eclipse on the night of January 20-21, the last before 2022.
For Europeans and Africans, the total eclipse will occur at the end of the night, just before dawn. The east of these continents will see less due to the rise of the day.
For North and South Americans, it will be early or midnight.
The full moon will be in the shadow of the Earth from 3:34 to 06:51 GMT. During the first hour, it will be delicately "eaten" from the left. The eclipse will be total for one hour starting from 04H41 GMT, according to the timetable provided by NASA.
The total phase of the eclipse will be about three quarters shorter than the great eclipse of July 2018, which will remain the longest in the 21st century.
During the total eclipse, the Moon will not be invisible: it will be red, as in all the total eclipses.
This shade will be due to the fact that the sun's rays will not reach it directly. Instead, a small part of the red rays will be filtered from the Earth's atmosphere and refracted towards the Moon (the blue rays will diverge towards the outside).
It is the same phenomenon that colors the sunrises and sunsets seen from the Earth in red.
"This is the last chance before a long time to see a total lunar eclipse," says AFP Bruce Betts, chief scientist of the Planetary Society, an American astronomical organization.
The next total eclipse visible from Europe will take place on May 16, 2022, but in the meantime partial eclipses will occur.
Total lunar eclipses can happen two or three times a year.
They correspond to a rare combination of circumstances: the Earth must be exactly between the Sun and the Moon.
It is still necessary for the sky to be unobstructed to enjoy it. Clouds often ruin the show.
Astronomy enthusiasts will be able to compare the small variations in the red hue of the Moon this time. "It all depends on what's in the atmosphere," says Bruce Betts. "Just as the sunsets change color from one day to the next, the eclipses vary depending on the particles in the atmosphere, or if there is a volcanic eruption, for example."
No telescope is needed to observe the eclipse. To see the craters of the Moon, the planetologist remembers that simple binoculars can do the trick.