Rafael Bachiller
Updated Thursday, January 25, 2024-14:52
This Thursday, January 25, the first of the 12 full moons of 2024
takes place
, among which we will find
four "supermoons"
and
two eclipses
.
As in 2024, on January 25 of the year 2043, 2062 and 2396 there will also be a full moon, here we explain why.
Full Moons
The
full moon
occurs when the Earth is in a straight line between the Sun and the Moon.
At this moment, the lunar disk appears completely illuminated and with a very intense shine.
This practically vertical illumination makes it easy to locate the main features of the visible side of the moon, such as the seas and the largest craters.
On the night of the full moon, sunrise occurs at sunset and lunar sunset at sunrise.
Although the full moon happens at a precise moment, we can see the lunar disk completely illuminated and very round throughout that night.
Heliocentric model, Andreas Cellarius (1661)
2024 lunar calendar
The average time between two full moons is called a "lunation" and, on average, is 29.53 days.
Therefore, a year (comprising 365 or, like this, 366 days) consists of 12.37 lunations.
Some years (as happened in 2023) may have 13 full moons, but the most common thing is for a year to contain twelve full moons, one in each month of the year.
That's what happens in 2024 and these are the dates of the full moons in each season:
Winter
: January 25, February 24,
Spring
: March 25, April 24, May 23
Summer
: June 22, July 21, August 19, September 18
Fall
: October 17, November 15, December 15
Two supermoons and two eclipses
In its elliptical orbit around the Earth, the distance of our satellite changes, reaching almost 407,000 kilometers at the times when it is furthest away (the apogee).
In its closest positions, its distance can drop to less than 357,000 kilometers (the perigee) and, therefore, on these occasions the Moon appears to us with a larger apparent size.
The lunar orbitRB
Although they are not official names in astronomy, we usually speak of a
"supermoon"
when the Moon is less than 360,000 kilometers from the Earth.
Similarly, a "minimoon" occurs when its distance from Earth exceeds 405,000 kilometers.
Keep in mind that there is not a huge difference between a supermoon and a minimoon: it is, at most, a 14% difference in the apparent diameter of the lunar disk.
Don't expect a supermoon to fill half the sky or anything like that.
However, it is an appreciable difference, and the supermoons have become a pretext to draw attention to our beautiful satellite.
During 2024, we will be able to enjoy two supermoons: the one on September 18 and the one on October 17.
The ones on February 24 and March 25 will be minimoons.
The full moon phase is when lunar eclipses can occur.
In 2024, we will have two of them, but neither very spectacular.
The first very subtle one (prenumbral type) will occur during the full moon on March 25.
The second lunar eclipse of the year, which will be partial and very weak, will take place on September 18;
only this will be visible from Spain.
The lunar phasesOrion 8 CC BY-SA 3.0
Christian celebrations
The first full moon of spring is of great importance for Christians, as it sets the date of
Easter
Sunday .
As this year the full moon will take place on Monday, March 25, Easter Sunday will be on the 31st of this same month.
Therefore, March 29 will be Good Friday, a national holiday.
In fact, that
first spring full moon
determines the dates of
Lent
.
Thus, the beginning of Lent, Ash Wednesday, is celebrated six and a half weeks before Easter Sunday;
In 2024 it will therefore be February 14, coincidentally coinciding with Valentine's Day.
And the six Sundays of Lent will be those that follow this Wednesday before Easter Sunday.
lunar cycles
Except for February, each month of the year is longer than one lunation and each year has 12.37 lunations.
Therefore, the dates of the lunar phases change from month to month and from year to year.
However, there are large cycles during which the dates of the lunar phases repeat.
The most famous of these cycles is the one found by the Greek astronomer Meton (born around 260 BC).
This is a cycle with a period of 19 years, a value that is a common approximate multiple of the orbital periods of the Earth and the Moon and is equivalent to 235 lunations (with a difference of only about two hours).
If we start from a date, for example,
the full moon on January 25, 2024
and follow this cycle, after exactly 19 years almost exactly 235 lunations will have passed and the full moon that makes the number 236 (the first of the following cycle, 19 years later) must also fall on the same date of the year.
That is why there will be a full moon on January 25 in the years 2043, 2062, 2081, etc.
However, due to the small difference between the duration of 19 years and 235 lunations, there may sometimes be a difference of one day between the date of a lunar phase and the same after a period.
Naturally the
Meto cycle
is also a cycle of
eclipses
.
There are other similar cycles that have been used throughout history, although less precise.
Thus the octaeteris of 8 years (approximately 99 lunations) or the tritos of 11 years (approximately 136 lunations).
Somewhat more precise is the 372-year cycle that provides the long-term recurrence of lunar phases.
Thus, we know that on January 25, 2396, the full moon will shine again.
Rafael Bachiller is director of the National Astronomical Observatory (National Geographic Institute) and an academic at the
Royal Academy of Doctors of Spain
.