On April 8th, 2024, portions of the United States
will get to enjoy the sight of a total solar eclipse.
The last time this took place was back in August of 2017.
So, this is a good time to refresh our memory as to what's going to happen,
why it occurs,
and let you know where you can watch the show in the sky.
A solar eclipse occurs when the Moon moves between the Earth and the Sun,
blocks the Sun's light and casts a shadow on the Earth.
When the Moon completely covers
the bright disk of the Sun, that's a total solar eclipse.
This differs from a lunar eclipse, where the Moon moves behind the Earth,
so it's now the Earth blocking the Sun's light on the Moon,
creating a shadow on it with a red tint.
To remember the difference,
just remember what object gets darker.
With a solar eclipse, it's the Sun,
and during a lunar eclipse, it's the Moon.
Because the Moon's shadow is relatively small,
a total solar eclipse is a pretty rare event to see.
In order to do so, you have to be on the sunny side
of the planet and within the path of the Moon's shadow.
And that path is affected by the Earth's rotation, Moon's orbit
and where they are in their orbit around the Sun.
There are a lot of moving parts that go into creating this incredible sight.
And speaking of parts, during a solar eclipse, the Moon is actually casting a shadow
consisting of two parts: The umbra and penumbra.
The Moon's umbra is the part of the Moon's shadow
where the entire sun is blocked by the Moon.
In space, it's a cone extending about 232.000 miles behind the Moon.
It's when the small end of this cone hits the Earth
that a total solar eclipse can be seen.
Those factors are why only a limited number of locations on Earth
get to actually see it.
So, if you find your area in the path of totality this year, treasure the sight -
because on average, that same spot on Earth won't see another
total solar eclipse for 375 years.
The area around Carbondale, Illinois, however, has hit the cosmic jackpot -
getting to experience this year's eclipse, as well as the one from 2017.
But their next view of a total solar eclipse
won't happen until the year 2343.
When you check out an eclipse map that depicts the path of totality,
keep this in mind:
While many maps will show a circle representing the Moon's shadow,
the true shape of the umbra
is more like an irregular polygon with slightly curved edges.
This is due to the fact that the Moon isn't a smooth sphere.
It has mountains, valleys and craters on its surface -
all of which affect the passing sunlight and shape of the resulting shadow.
NASA's Lunar Reconnaissance Orbiter spacecraft,
which has been orbiting the Moon since 2009, has provided scientists
with incredibly detailed photographs, terrain maps, and other sets of data
that have allowed us to better understand the shape of the Moon's surface.
This, in turn, has given us the ability to create more finely detailed maps
depicting which specific areas on Earth lie within the solar eclipse’s path of totality.
Regions outside the narrow path,
depending on their distance from it,
will get to witness a partial eclipse to varying degrees.
As you can see, the penumbra shadow passes over almost all of North and Central America,
as well as Greenland, Iceland and the Western British Isles.
This 2024 total solar eclipse is therefore giving millions of people
the opportunity to share in this rare and dynamic interaction
between our Earth, Sun and Moon.