What if we had no Moon?
Or what if the we had a Moon like we do now and it suddenly disappeared?
Find out what would happen.
1.) There’d be no such thing as eclipses on Earth.
Without the Sun, Moon and Earth, there would be no eclipses. The Sun
is constantly shining on Earth, casting a shadow for over a million
miles (and over a million kilometers) in its wake. Yet without our Moon —
just a few hundred thousand miles (or kilometers) away — there’d be no
object that would pass through the Earth’s shadow; there’d be no lunar
There’d also be no solar eclipses: no annular, partial, or total eclipses. The Moon’s shadow is almost exactly
equal in length to the Earth-Moon distance; without the Moon, no
shadow, and no disc to block the Sun’s disk. The next largest object
that can pass in between the Earth (after the Moon) is Venus, and while it’s incredibly cool when that happens, that’s the closest we’d get to an eclipse without the Moon.
2.) Our tides would be tiny in comparison to what they are now, and they’d be dominated by the Sun.
Although the Sun is some 400 times larger (in diameter) than the
Moon, it’s also, on average, about 400 times farther away. This explains
why they appear about the same angular size from Earth. But the Sun is only about 27 million times as massive as the Moon.
Why in the world would I say “only” there? Because it would have to be about (400)3 times the mass of the Moon, or 64 million
times its mass, in order to have the same effect on Earth’s tides as
our small, lunar neighbor. As it stands, tides from the Sun are only
about 40% as strong as tides from the Moon. When the Sun and Moon line
up in either the “new” or “full” Moon phases, we get spring tides, 140%
as large as a typical tide, and when they’re at right angles, we get
neap tides, only 60% as strong as a standard tide.
3.) Nights would be much, much darker than we’re used to.
If you’ve ever been outside in the wilderness on a totally moonless
night, without any artificial light, you probably noticed two things.
First, the night sky is absolutely breathtaking; you can see thousands
upon thousands of stars, the plane of the Milky Way, and even dozens of
extended, deep-sky objects with your naked eye alone. And second, you
can’t see a damned thing in front of your own face.
The Sun is much, much brighter than the Moon; the full Moon is just 1/400,000th as bright as the daylight Sun. Yet Venus, the next brightest object in the night sky, is only 1/14,000th as bright as the full Moon!
But that wouldn’t be the biggest difference, not by a long shot.
4.) A day on Earth would be much, much shorter; only about 6-to-8 hours, meaning there’d be between about 1,100-1,400 days in a year!
Our 24-hour-days may seem like they don’t change from one year to the
next. In reality, the change is so tiny that it took centuries to
perceive, but the Earth’s rotation slows down ever so slightly over
time, thanks to the tidal friction provided by the Moon. The slow-down
is very, very slow (on the order of microseconds-per-year), but over millions and even billions of years, it adds up!
In about 4 million years, we’ll no longer need leap years to keep our
calendars on track. If the Sun would live an infinite amount of time,
the Earth would eventually slow down and become tidally locked to the
Moon, the same way the Moon is locked to us and always shows us the same
face. Instead of 24 hours, a day would last for some 47 current Earth days. (In reality, the Sun will end its life long before that happens, so no worries there.)
But in the meanwhile, we can use what we know to extrapolate backwards in time, and we find that in order to get a 24 hour day today, the Earth had to have been spinning much faster in the past: about three-to-four times as fast more than four billion years ago! If we didn’t have a Moon — if we never
had our Moon — the day would be much, much shorter than it is today,
and our planet would have a larger equatorial bulge, much more flattened
poles, and over 1,000 days in a year!