What If We Lost Our Moon?

Earthquakes, tidal waves, climatic chaos are just a few of the possible outcomes of losing the moon. Good thing this is just science fiction. Continue reading →

Today I was asked a question that was motivated by the new movie Oblivion: What would happen to the Earth if the moon was destroyed? "I dunno," I replied, "What does happen when the moon is destroyed?" When the expected why-the-chicken-crossed-the-road response didn't come, I decided I'd better try and answer the question.

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The first thing that came to mind is that it depends on the manner of the moon's destruction. If it was, say, zapped to bits by a Death Star and those bits still floated in a cluster in the same orbit, I expect they would exert the same gravitational pull on Earth as does the intact moon, and not much would change on Earth.

We'd no longer watch the phases of the moon at night, but see a glittering cloud of debris which would probably be a lot brighter than the full moon, what with all those zillions of little surfaces to reflect sunlight. I know some astronomers who would really hate this new interference with their dark skies.

But if the moon were dragged off and completely removed, there would be none of its mass left to tug gravitationally on the Earth. One of the effects would be that we could throw out tide tables for good.

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The ocean tides would still happen, but the bulge of water would follow the sun, so you could expect high tides around noon everywhere, everyday. I know some fishermen who would appreciate this.

Since the solid Earth flexes tidally, it makes sense that there might be some internal grumbling when Earth loses the moon. Earthquakes. Maybe a few volcanoes getting rowdy. That kind of stuff. But there's no reason to worry (or hope) that California will fall into the Pacific. Sorry New York. Sorry Las Vegas.

The greater concern would be in the long-term, regarding the Earth's wobbling spin axis. Right now the spin axis of the Earth very slowly wobbles over 26,000 years, like a slowing wobbling top, because of the tug of the sun. The wobble causes true north to not always point at Polaris, a.k.a., the North Star. Experts agree that the moon acts sort of like a shock absorber to this wobble - keeping it from getting out of hand (see the nitty gritty details in this SETI talk).

It's possible that Earth without a moon would wobble wildly, sort of like Mars does. The Red Planet's wobble is so extreme that it may be the cause of some cycles of climate change there. If the same thing happened here, Earth might wobble so much that seasons would become inhospitably extreme and Earth would be a much less stable and habitable planet.

Without the moon the tilt of the Earth's axis could go from its current wobble of 22 to 25 degrees to a wide ride of zero to 85 degrees - zero would eliminate seasons, and 85 is basically the Earth leaning over on its side. If this happened, the current crisis we call global warming would be a very pleasant tea party by comparison.

Luckily, the wobbling would not affect things right away but over many millions of years.

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Until then, we would be busy observing how the loss of the moon messes up the lives of other animals, ruins whole genres of music, poetry, and photography, and we'd probably go extinct just out of sheer boredom.

That's assuming we survived the alien invaders who destroyed the moon in the first place. Which, to me, raises an even more pressing question: Why would they do that?

Image credit: NASA

Western Hemisphere Feb. 24, 2012 -- We at Discovery News are loving the new photos of Earth coming in from VIIRS, the biggest and most important instrument of the five aboard NASA's Earth-observing satellite - Suomi NPP. These composite images are put together using a number of swaths of the Earth's surface taken with the Visible/Infrared Imager Radiometer Suite (VIIRS) over the course of a day as the Suomi NPP satellite orbits the planet from pole to pole. Here we see the western hemisphere from swaths taken on Jan. 4, 2012.

Eastern Hemisphere The Suomi NPP satellite flew over the eastern hemisphere six times during an eight hour time period on Jan 23, 2012. NASA scientist Norman Kuring took those six sets of data and combined them into this image shown here.

Australian View Here NASA scientist Norman Kuring has done the same with the VIIRS data sets taken on Feb. 8, 2012.

Arctic View The newly launched Suomi National Polar-orbiting Partnership (S-NPP) satellite, which was blasted into space on Oct. 28, 2011, circled the Earth 15 times to capture the visual data used for the stunning picture.

BIG PIC: White Marble View Over Arctic

Hot and Cold Here we see the results of the Clouds and the Earth's Radiant Energy System (CERES) instrument at work on the Suomi NPP satellite. "In the longwave image, heat energy radiated from Earth (in watts per square meter) is shown in shades of yellow, red, blue and white. The brightest-yellow areas are the hottest and are emitting the most energy out to space, while the dark blue areas and the bright white clouds are much colder, emitting the least energy. Increasing temperature, decreasing water vapor, and decreasing clouds will all tend to increase the ability of Earth to shed heat out to space," the NASA CERES team explained.

Keeping Up with the Sun From its vantage 824 kilometers (512 miles) above Earth, the Visible Infrared Imager Radiometer Suite (VIIRS) on the NPOESS Preparatory Project (NPP) satellite gets a complete view of our planet every day. This image from Nov. 24, 2011, was the first complete global image from VIIRS. Rising from the south and setting in the north on the daylight side of Earth, VIIRS images the surface in long wedges measuring 3,000 kilometers (1,900 miles) across. The swaths from each successive orbit overlap one another, so that at the end of the day, the sensor has a complete view of the globe. The Arctic is missing because it is too dark to view in visible light during the winter. The NPP satellite was placed in a Sun-synchronous orbit, a unique path that takes the satellite over the equator at the same local (ground) time in every orbit. So, when NPP flies over Kenya, it is about 1:30 p.m. on the ground. When NPP reaches Gabon—about 3,000 kilometers to the west—on the next orbit, it is close to 1:30 p.m. on the ground. This orbit allows the satellite to maintain the same angle between the Earth and the Sun so that all images have similar lighting. The consistent lighting is evident in the daily global image. Stripes of sunlight (sunglint) reflect off the ocean in the same place on the left side of every swath. The consistent angle is important because it allows scientists to compare images from year to year without worrying about extreme changes in shadows and lighting. PHOTOS: Sunsets and Other Sky Wonders

Final Checks Electro Magnetic Interference testing of the Suomi NPP satellite at the Ball Aerospace facility.

Behind the Scenes By stitching six swaths together, NASA scientist Norman Kuring takes the Suomi NPP satellite perspective from its polar orbit around Earth at an altitude of 512 miles (about 824 kilometers), and changes it to a 'Blue Marble' view as though it were seen from 7,918 miles (about 12,743 kilometers).

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