graphic illustration showing the moon between the sun and earth, casting a shadow on our planet.

Eclipse seasons — Why the lunar eclipse on March 25 occurs 2 weeks before the total solar eclipse on April 8

On Monday, March 25, the total “Worm Moon” will trigger a penumbral lunar eclipse for the night time aspect of Earth, together with North and South America, Europe, East Asia, Australia and New Zealand.

The third full moon of 2024 and the primary of spring within the northern hemisphere, the “Worm Moon” — also referred to as the “Crow Moon” and the “Lenten Moon” — will transfer via the Earth‘s outer shadow in area.

In addition to being an attention-grabbing astronomical occasion, it should arrange a complete photo voltaic eclipse precisely two weeks later that shall be seen throughout North America.

We’re coming into 2024’s first (and greatest) “eclipse season,” throughout which there shall be two eclipses — considered one of the moon by the Earth and one of many solar by the moon.

  • A lunar eclipse happens throughout a full moon — when the Earth is between the solar and moon, blocking daylight from reaching the lunar floor. 
  • A photo voltaic eclipse happens throughout a new moon — when the moon is between the Earth and the solar. 

‘Eclipse seasons’ defined

A penumbral lunar eclipse on March 24/25 will put the moon heading in the right direction to trigger a complete photo voltaic eclipse on April 8. This picture exhibits a penumbral lunar eclipse from Might 2023. (Picture credit score: Liu Debin/VCG through Getty Photographs)

Each 173 days, for between 31 and 37 days, the moon intersects (or virtually intersects) the ecliptic—the obvious path of the solar via our daytime sky. The ecliptic can also be the airplane of Earth’s orbit of the solar. What outcomes is a brief season throughout which two — and infrequently three — photo voltaic and lunar eclipses can happen.

Eclipse seasons in 2024

In 2024, there shall be two eclipse seasons every that includes two photo voltaic eclipses and two lunar eclipses:  

Eclipse season 1 

  • March 25: a penumbral lunar eclipse of the “Worm Moon” (North and South America, Europe, East Asia, Australia and New Zealand). 
  • April 8: a complete photo voltaic eclipse (components of Mexico, the U.S. and Canada). 

Eclipse season 2 

  • September 18: a partial lunar eclipse of the “Harvest Moon” (Europe, Asia, Africa, North America, South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica.) 
  • October 2: an annular photo voltaic eclipse (Easter Island, Rapa Nui, Chile and Argentina). 

Though there is no such thing as a third eclipse in 2024’s second eclipse season, there so practically is. In response to timeanddate, an “virtually lunar eclipse” will (will not!) happen on October 17 when the total “Hunter’s Moon” simply misses shifting via Earth’s shadow. It is a meaningless truth, visually, nevertheless it helps reveal how eclipse seasons work. It would miss as a result of the moon may have been at its ascending node the day earlier than, in line with Astropixels

The moon’s orbital nodes are why there is not a photo voltaic or lunar eclipse each month. 

How the moon’s orbital nodes work

The moon’s shadow solely hits the Earth when the road of nodes is pointed towards the solar. (Picture credit score: NASA’s Scientific Visualization Studio)

The moon’s orbit of Earth is tilted by 5 levels with respect to the ecliptic. That ensures that there normally is not a photo voltaic or lunar eclipse in any given month, nevertheless it additionally ensures that they have to occur sometimes.

For one to happen, the moon should attain its new or full section whereas it crosses the ecliptic. These two locations are referred to as the ascending node and the descending node. 

The moon reaches these two nodes at completely different instances each month. It normally does so when it is not both new or full, so it is not able to eclipse or be eclipsed. Solely throughout an eclipse season does the moon arrive at, or very near, these nodes on the good time to trigger an eclipse. The result’s a brief season throughout which two (and generally three) photo voltaic and lunar eclipses can happen, one after one other, two weeks aside. 

What causes partial and penumbral eclipses

Slight eclipses — a partial photo voltaic or lunar eclipse and a penumbral lunar eclipse — happen throughout eclipse season when the moon reaches a node only a few hours or a day too early or late. On these events, it misses its goal, both eclipsing solely a part of the solar or shifting via Earth’s outer shadow. 

Both the brand new moon is barely above or beneath the solar, and the full moon is above or beneath Earth’s shadow. Solely when it reaches a node at exactly the precise time does it trigger a complete photo voltaic eclipse or a complete lunar eclipse.

That is what makes Monday, April 8, such a special occasion for North America — and why you must, if potential, journey into the trail of totality. Solely then will you see, with your personal bare eyes, the solar’s majestic, spiky white corona revealed in a darkish sky. 

Notice: Solely have a look at the partial phases of any photo voltaic eclipse with correct eye safety, which suggests photo voltaic eclipse glasses. Lunar eclipses are fully secure always.

Associated: The right way to observe the solar safely (and what to search for)