Las Vegas Sun

March 29, 2024

5-MINUTE EXPERT:

Get to know the moon

Supermoon and Lunar Eclipse Around the World

Charlie Riedel / AP

A couple sits on a bluff overlooking the Missouri River as the full moon rises in the distance Monday, Sept. 28, 2015, in Kansas City, Mo.

Did you know?

The moon is around 238,855 miles ­away from Earth. About 30 Earths could fit between the two. Each year, it moves about 1 inch farther away.

Harvest, blood, full, blue — the moon by any name does not, in fact, shine the same. No matter which phase of the lunar cycle it’s in, however, one constant is that it always shows us the same face. Because of the way the moon and Earth’s fields of gravity interact, the same side is always facing us. In fact, the far side wasn’t even seen by human eyes until the Soviet Luna 3 spacecraft photographed it in 1959. Here’s how it happens.

What are we looking at?

The moon is a terrestrial body with a molten core, mantle and crust, much like Earth and other solid planets. Because the moon’s atmosphere is thin, we can observe its surface from afar without interference.

Referring to its “dark side” is not accurate, as the entire surface of the moon receives sunlight at some point during the lunar cycle. It’s correct to refer to the two hemispheres as the near side (what we see here on Earth) and far side (hidden from our view). The two look very different.

The near side is home to large swaths of maria, low-elevation areas that used to be filled with lava from ancient volcanoes. They appear darker, while the highlands appear light.

Maria are sparse on the far side. Scientists think it may be because the crust there is thicker, preventing magma from breaking the surface. Many impact craters from meteorites and comets are visible, as the thin atmosphere doesn’t burn them up.

How it works

The moon rotates on its axis as it orbits us, the same way the Earth rotates as it orbits the sun. The difference is that the moon’s rotation and orbit are synchronous, meaning they both occur at approximately the same speed. One orbit and one rotation take approximately 28 days.

If you were to view the phases of the moon in time-lapse, however, it would appear to “wobble” in the sky. This is known as libration and is due to the moon’s orbit not being a perfect circle. It rotates slightly slower when it is at perigee (the point in its orbit closest to Earth) and faster when it’s farthest away, at apogee.

The phases of the moon are not precisely timed to its orbit, but sometimes can coincide to make the moon seem especially large (a supermoon) or small (a micromoon).

Recent and upcoming lunar events

Did you know?

International law prohibits any country from owning or using the moon or any other celestial body for weapons testing or other military purposes.

• Harvest moon, Oct. 16: The first full moon after the autumnal equinox (Sept. 22). Sometimes called the Blood Moon.

• Super full moon, Nov. 14: When a full moon coincides with perigee, it appears about 7percent larger in the sky. Not to be confused with instances when the moon is closer to the horizon and appears larger in the sky. This is an optical illusion caused by Earth’s atmosphere and not related to its position in orbit.

• Penumbral lunar eclipse, Feb. 11, 2017: Visible at moonrise in Nevada, the next lunar eclipse isn’t until next year. It will be a penumbral eclipse, where the moon will pass behind the shadow of the Earth. It won’t totally disappear behind the darkest part (the umbra) of the shadow, though, which happens during a total eclipse.

• Total solar eclipse: Aug. 21, 2017: There will be an annular (where the moon doesn’t cover the entire sun, leaving a bright ring of fire around the moon’s shadow) solar eclipse earlier in 2017, but it won’t be visible in our hemisphere. However, Nevadans will be able to view a total eclipse in August.

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