What is the massive thing under the Moon’s surface?

A surprise on the far side of the Moon.

Image source: NASA/Goddard Space Flight Center/University of Arizona
  • Scientists detect a gigantic, underground, metallic anomaly down a crater on the Moon.
  • "Whatever it is, wherever it came from," it looks to be billions of years old.
  • It's probably the remains of an asteroid that hit the Moon.

"Imagine taking a pile of metal five times larger than the Big Island of Hawaii and burying it underground. That's roughly how much unexpected mass we detected." That's Peter B. James of Baylor University talking about a gigantic anomaly found beneath the Moon's surface. He's the lead author of a study published in Geophysical Research Letters describing the odd find. There are a few theories about what it could be.

Mystery mass

China's Yutu-2 rover departs from the Chang'e-4 lander on the Moon's far side.

Image source: CNSA/CLEP

The thing sits beneath the Moon's South Pole-Aitken basin, believed to be the largest intact crater in our solar system. The oval-shaped feature is thought to be about 4 billion years old, and it's big: about 2,000 kilometers across at some points. Situated on the far side of the Moon, it can't be directly seen from Earth. Even so, James calls it, "one of the best natural laboratories for studying catastrophic impact events, an ancient process that shaped all of the rocky planets and moons we see today."

In studying the basin, James and his colleagues pored through data from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission to document changes in the strength of the Moon's gravity. "When we combined that with lunar topography data from the Lunar Reconnaissance Orbiter," says James, "we discovered the unexpectedly large amount of mass hundreds of miles underneath the South Pole-Aitken basin." He says "whatever it is, wherever it came from," it's pulling down the floor of the crater by more than half a mile.

So, erm, what is it?

Peter B. James.

Peter B. James.

Image source: Baylor University

The two most likely theories are that it's the iron-nickel core of a long-ago asteroid impact, or that it's a leftover clump of dense oxides from the cooling of the Moon's magma. Or, sure, a giant spaceship or hidden underground civilization, ahem.

James says, "We did the math and showed that a sufficiently dispersed core of the asteroid that made the impact could remain suspended in the Moon's mantle until the present day, rather than sinking to the Moon's core."

It's an intriguing find, and with ongoing international efforts to study the Moon's far side — such as China's Chang'e 4 mission — we look forward to further insights on this huge anomaly.

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Photo: Luisa Conlon , Lacy Roberts and Hanna Miller / Global Oneness Project
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Experts are already predicting an 'active' 2020 hurricane season

It looks like a busy hurricane season ahead. Probably.

Image source: Shashank Sahay/unsplash
Surprising Science
  • Before the hurricane season even started in 2020, Arthur and Bertha had already blown through, and Cristobal may be brewing right now.
  • Weather forecasters see signs of a rough season ahead, with just a couple of reasons why maybe not.
  • Where's an El Niño when you need one?

Welcome to Hurricane Season 2020. 2020, of course, scoffs at this calendric event much as it has everything else that's normal — meteorologists have already used up the year's A and B storm names before we even got here. And while early storms don't necessarily mean a bruising season ahead, forecasters expect an active season this year. Maybe storms will blow away the murder hornets and 13-year locusts we had planned.

NOAA expects a busy season

According to NOAA's Climate Prediction Center, an agency of the National Weather Service, there's a 60 percent chance that we're embarking upon a season with more storms than normal. There does, however, remain a 30 percent it'll be normal. Better than usual? Unlikely: Just a 10 percent chance.

Where a normal hurricane season has an average of 12 named storms, 6 of which become hurricanes and 3 of which are major hurricanes, the Climate Prediction Center reckons we're on track for 13 to 29 storms, 6 to 10 of which will become hurricanes, and 3 to 6 of these will be category 3, 4, or 5, packing winds of 111 mph or higher.

What has forecasters concerned are two factors in particular.

This year's El Niño ("Little Boy") looks to be more of a La Niña ("Little Girl"). The two conditions are part of what's called the El Niño-Southern Oscillation (ENSO) cycle, which describes temperature fluctuations between the ocean and atmosphere in the east-central Equatorial Pacific. With an El Niño, waters in the Pacific are unusually warm, whereas a La Niña means unusually cool waters. NOAA says that an El Niño can suppress hurricane formation in the Atlantic, and this year that mitigating effect is unlikely to be present.

Second, current conditions in the Atlantic and Caribbean suggest a fertile hurricane environment:

  • The ocean there is warmer than usual.
  • There's reduced vertical wind shear.
  • Atlantic tropical trade winds are weak.
  • There have been strong West African monsoons this year.

Here's NOAA's video laying out their forecast:

But wait.

ArsTechnica spoke to hurricane scientist Phil Klotzbach, who agrees generally with NOAA, saying, "All in all, signs are certainly pointing towards an active season." Still, he notes a couple of signals that contradict that worrying outlook.

First off, Klotzbach notes that the surest sign of a rough hurricane season is when its earliest storms form in the deep tropics south of 25°N and east of the Lesser Antilles. "When you get storm formations here prior to June 1, it's typically a harbinger of an extremely active season." Fortunately, this year's hurricanes Arthur and Bertha, as well as the maybe-imminent Cristobal, formed outside this region. So there's that.

Second, Klotzbach notes that the correlation between early storm activity and a season's number of storms and intensities, is actually slightly negative. So while statistical connections aren't strongly predictive, there's at least some reason to think these early storms may augur an easy season ahead.

Image source: NOAA

Batten down the hatches early

If 2020's taught us anything, it's how to juggle multiple crises at once, and layering an active hurricane season on top of SARS-CoV-2 — not to mention everything else — poses a special challenge. Warns Treasury Secretary Wilbur Ross, "As Americans focus their attention on a safe and healthy reopening of our country, it remains critically important that we also remember to make the necessary preparations for the upcoming hurricane season." If, as many medical experts expect, we're forced back into quarantine by additional coronavirus waves, the oceanic waves slamming against our shores will best be met by storm preparations put in place in a less last-minute fashion than usual.

Ross adds, "Just as in years past, NOAA experts will stay ahead of developing hurricanes and tropical storms and provide the forecasts and warnings we depend on to stay safe."

Let's hope this, at least, can be counted on in this crazy year.

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