Look Up! This Is Your Last Chance to See a Blue Moon Until 2020

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iStock

Lately, blue moons haven't been as rare as their reputation suggests. The last one appeared at the tail-end of January and coincided with a super moon and a total lunar eclipse. The next blue moon is set to light up skies on March 31, and though it won't be accompanied by any of those celestial oddities this time, you shouldn't take it for granted: According to WZTV, this is your last chance to see one until 2020.

Unlike other events marking your meteorological calendar, blue moons aren't affected by anything going on in space so much as the date they happen to land on. A blue moon is the second full moon to occur within a single calendar month. The previous full moon fell on March 2, making it the last full moon of winter as well as a Full Worm Moon (that's an Old Farmer's Almanac term for a full moon that occurs when birds start searching for worms at the end of winter).

Although a blue moon is indistinguishable from a regular full moon, sky gazers have an additional reason to step outside on the night of March 31: Mercury will be close to Venus in the sky above the western horizon, making the solar system's smallest planet especially visible. The best time to spot it will be right after sunset, after which spectators can stick around to watch the full moon rise.

If you miss the blue moon this time around, you have more than two years to prepare for the next one. It's set to arrive on Halloween night 2020, so start planning your blue werewolf costume now.

[h/t WZTV]

If the Moon is Gradually Moving Farther Away From Us, Will Its Gravitational Pull Ever Cease on Earth?

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iStock.com/kyoshino

Robert Frost:

The Moon is receding from the Earth, but will not continue to do so forever. We have to consider why the Moon is moving away at around 1.5 inches (3.78 cm) per year—a force is necessary to cause that.

The Moon exerts a tidal force on the Earth, causing a bulge. But, because the Earth rotates, that bulge is not directly between the Earth and Moon. It is slightly in front. That bulge has a gravitational pull on the Moon, causing it to move forward, slightly faster.

Causing the Moon to move slightly faster results in it climbing very slowly to a higher orbit. The Moon climbs higher by about 3.78 cm per year. But, since we just said that the force is gravitational and we know that gravity decreases with distance, we know that the force will also decrease with distance.

That means the rate at which the Moon recedes will decrease with time. But there's more to it than that. A force acts upon both bodies. While the impact on the Moon is causing it to recede, the impact on the Earth is that it is being caused to slow its rotation. The day is getting longer.

Eventually, the length of the day will match the orbital period of the Moon. That means both bodies will be tidally locked—meaning the same part of the Earth will always face the same part of the Moon. And if that happens, there is no longer a leading bulge and thus no longer a force causing the Moon to move away.

This would happen when the orbital period of the Moon is about 47 days. That would put the Moon at a distance of about 550,000 km; less than half as far again as it is today. In other words, not very far.

However, it will take a long time for that to happen. In the meantime, the Sun will turn into a red giant and its outer layers will extend to where Mars is today, meaning Earth, the Moon, and every In-N-Out restaurant will have been swallowed up and turned into loose atoms.

This post originally appeared on Quora. Click here to view.

The Northern Lights May be Visible in New York, Michigan, and Illinois on Saturday

iStock.com/den-belitsky
iStock.com/den-belitsky

The Northern Lights, a meteorological event most common to areas north of the Arctic Circle, may be visible over parts of America this weekend, Newsweek reports. Due to a solar storm, the light show may appear Saturday night over states in the northern part of the contiguous U.S., including New York, Michigan, Illinois, and Washington state.

Aurora borealis, or the Northern Lights, occur when solar particles react to gases in Earth's atmosphere. Magnetic energy exaggerates this effect, which is why auroras most often appear at the geomagnetic poles where Earth's magnetic field is strongest. Rare circumstances can produce this phenomenon at lower latitudes, which may be the case this weekend.

On Wednesday, March 20, a solar flare sent a blast of solar particles toward Earth. The resulting geomagnetic storm could make for a vibrant and colorful aurora reaching as far south as New York and Wisconsin.

To catch the spectacle, look up at the night sky on Saturday, March 23. People in areas with minimal light pollution have the best chance of seeing the Northern Lights, though cloudy weather may make them hard to see.

[h/t Newsweek]

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