Earth tipped over on its side 84 million years ago and then righted itself, new study finds

NASA's Earth Polychromatic Imaging Camera image of earth
A photo of Earth taken by NASA’s Earth Polychromatic Imaging Camera (EPIC).

If you’d been able to stare at Earth from space during the late Cretaceous, when Tyrannosaurus rex and Triceratops roamed, it would’ve looked like the whole planet had tipped over on its side.

According to a new study, Earth tilted by 12 degrees about 84 million years ago.

“A 12-degree tilt of the Earth could affect latitude that same amount,” Sarah Slotznick, a geobiologist at Dartmouth College and co-author of the new study, told Insider.

It would approximately move New York City to where Tampa, Florida, is right now, she added.

Imagine the Earth as a chocolate truffle – a viscous center ensconced in a hardened shell. The center consists of a semi-solid mantle that encircles the liquid outer core. The top layer of the truffle, the Earth’s crust, is fragmented into tectonic plates that fit together like a puzzle. Continents and oceans sit atop these plates, which surf atop the mantle.

The researchers found that, between 86 and 79 million years ago, the crust and mantle had rotated around Earth’s outer core and back again – causing the entire planet to tilt and then right itself like a roly-poly toy.

Using magnetic rocks to track the Earth’s tipping

illustration of earth's core/mantle layers
An artist’s conception of the different layer’s of our planet, including the crust, mantle, and inner and outer cores.

Scientists can piece together a picture of which tectonic plates were where millions of years ago by analyzing what’s known as paleomagnetic data.

When lava at the junction of two tectonic plates cools, some of the resulting rock contains magnetic minerals that align with the directions of Earth’s magnetic poles at the time the rock solidified. Even after the plates containing those rocks have moved, researchers can study that magnetic alignment to parse out where on the global map those natural magnets existed in the past.

The study authors examined the magnetic alignment of ancient limestones they collected from Italy and found Earth’s crust was moving about 3 degrees every million years during its tilt and tilt back.

“We never suspected we would see this full round-trip event,” Ross Mitchell, a geophysicist at the Chinese Academy of Sciences and Slotznick’s co-author, told Insider.

A sinking tectonic plate may have caused Earth to tilt

earth moon near 1998 jhuapl nasa
NASA’s asteroid-bound NEAR spacecraft took this mosaic image of Earth and the moon in January 1998.

Imagine that the Earth is like a spinning top: If the top’s weight is evenly distributed, it should whirl perfectly, without any wobbling. But if some of the weight were to shift to one side or the other, that would change the top’s center of mass, leading it to tilt toward the heavier side as it spins.

According to Slotznick, upwellings of hot rock and magma – known as mantle plumes – from the outer core towards the crust may have played a role in altering how Earth’s mass was distributed during the late Cretaceous.

But Mitchell said shifting tectonic plates could explain Earth’s ancient 12-degree tilt. When hotter, less dense material from deep within the mantle rises toward to the crust, and colder, denser material sinks towards the core, these plates can collide. Upon impact, one plate will subduct, or sink, under another.

Prior to the late Cretaceous, the Pacific Plate – the largest tectonic plate on Earth spanning 40 million square miles under the Pacific Ocean – was sinking under another plate to its north. Around 84 million years ago, the Pacific Plate started subducting in a different direction, under another plate to its west. This change “might have very well changed the literal balance of the planet,” Mitchell said.

He wasn’t surprised to find the Earth had reversed course and tilted back.

“The planet’s outer later behaves elastically like a rubberband and would have snapped back to its original shape after the excursion,” he said.

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Earth’s core is growing lopsidedly, a new study suggests – and it’s been doing that for at least half a billion years

Earth's core illustration
An illustration of Earth’s core.

Think of the Earth like a geological tootsie pop.

If you were to peer more than 3,000 miles below your feet into the planet’s center, you’d see a dense, solid ball of iron roughly three-quarters the size of the moon. That iron spheroid is the inner core, and it’s nestled inside the planet’s molten outer core.

The inner core is always growing: Its radius increases by a millimeter each year as pieces of molten iron in the outer core cool and solidify into iron crystals. Although temperatures in the inner core are high enough to liquify iron, the intense pressure that deep inside the planet prevents the crystals from melting – picture it like packing a hard snowball.

But according to a recent study published in the journal Nature Geoscience, the inner core is growing lopsidedly. One half of the sphere, the eastern half under Indonesia’s Banda Sea, accrues 60% more iron crystals than its western counterpart, which is located under Brazil.

“The west side looks different from the east side all the way to the center,” Daniel Frost, a seismologist at the University of California, Berkeley, who co-authored the new study, said in a release. “The only way we can explain that is by one side growing faster than the other.”

Asymmetric growth in the core

artist's illustration of iron crystal distribution earth's inner core
A graphic showing how iron crystals are distributed and move around in Earth’s inner core.

Although the Earth is more than 4 billion years old, its inner core is younger – geologists suspect it formed between half a billion and 1.5 billion years ago, when pieces of liquid iron from the outer core first started to crystallize.

Frost’s team created a computer model that tracked the inner core’s growth over the last billion years. They found that its lopsided nature likely began as soon the core formed.

Of course, if one half has been growing faster than the other for that long, the inner core’s shape should no longer be spherical. But that’s not the case. So Frost and his colleagues think that gravity may be compensating for the asymmetrical growth by pushing excess crystals from the core’s eastern side to its western side, thereby helping the core maintain a ball-like physique.

illustration of earth's core/mantle layers
An artist’s concept of Earth’s layers, including the crust, mantle, and inner and outer cores.

Frost’s team isn’t sure why iron crystals are forming unevenly in the inner core, but he said the answer likely lies in the layers above it – both the outer core and the mantle, a 1,800-mile-thick band of hot rock on which the tectonic plates float.

“Every layer in the Earth is controlled by what’s above it, and influences what’s below it,” Frost told Live Science.

If iron is crystallizing more quickly on one side of the inner core than the other, that must mean the outer core is cooling faster on that side. So the mantle on that side, in turn, must be cooling the outer core faster than the mantle on the other side.

The genesis of that cooling chain, Frost said, could be Earth’s tectonic plates. When one plate pushes up against another, one subducts, or sinks, below the other. The subducting plate cools the mantle in that area of the planet.

The core’s lopsided growth might impact Earth’s magnetic field

Magnetosphere earth magnetic field
An illustration of Earth’s magnetic field, in blue, as it protects the planet from solar radiation.

Earth’s core plays a key role in protecting the planet from dangerous solar wind and radiation. Swirling iron in the outer core generates a magnetic field that stretches all the way from there to the space surrounding our planet.

That swirl happens, in part, because of a process in which hotter, lighter material from the outer core rises into the mantle above. There, it swaps places with cooler, denser mantle material, which sinks into the core below. This is known as convection.

Convection also happens between the inner and outer core, so if various parts of the outer and inner core are cooling at different rates, that could affect how much heat gets exchanged at the boundary – which might have an impact on the swirling engine powering Earth’s protective sheath.

“The question is, does this change the strength of the magnetic field?” Frost told Live Science.

For now, his group isn’t sure, but Frost said he’s investigating the answer.

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A ‘ring of fire’ solar eclipse will be visible in the sky on Thursday. Here’s how to spot the rare event.

annular solar eclipse
An annular solar eclipse.

  • An annular solar eclipse will form in the sky at 6:53 a.m. ET on Thursday.
  • The phenomenon is marked by a bring circle of light, or ‘ring of fire,’ around the moon’s edge.
  • The sight is partially visible in the northeastern US but best seen from Canada and Russia.
  • See more stories on Insider’s business page.

A solar eclipse will be visible in the sky at 6:53 a.m. ET on Thursday, as the moon passes between the Earth and the sun.

During a total solar eclipse, the moon blocks the sun entirely. But Thursday’s spectacle is an annular solar eclipse, which occurs when the moon is too far from Earth – and therefore too small in the sky – to fully cover the sun. That leaves room for a brilliant halo of light, often referred to as a “ring of fire” or annulus, surrounding the moon.

The phenomenon won’t be visible everywhere: Parts of Canada, Greenland, and Russia will have the best views. People in the northeastern US, northern Europe, and northern Asia will be able to see a partial solar eclipse, which will look as if someone has taken a bite out of the sun.

This will be the only annular solar eclipse this year, though it’s the first of two solar eclipses in 2021. The year’s second solar eclipse – a total eclipse – will take place on December 4.

Annular solar eclipses are rare spectacles

A combination of photos depicts a partial annular solar eclipse observed with the use of a solar filter in Siak, Riau province, Indonesia, December 26, 2019. REUTERS/Willy Kurniawan
A partial annular solar eclipse observed with the use of a solar filter.

The glowing “ring of fire” in an annular eclipse is only visible for a short time: anywhere from a fraction of a second to over 12 minutes. Last year’s annular solar eclipse lasted just under 90 seconds.

Depending on your vantage point, you may still be able to see a band of light form along the moon’s edge, then disappear over the span of roughly three hours.

Total solar eclipses usually happen every five to six months, but annular solar eclipses only occur every year or two. That’s because they require a precise set of conditions: To start, the sun, moon, and Earth must all be aligned. The moon must also be close to its apogee, or farthest point from Earth – around 252,700 miles away.

In any solar eclipse, the moon’s shadow carves a path across the Earth. During a total solar eclipse, the darkest part of the moon’s shadow, called the umbra, hits the Earth. But during an annular solar eclipse – when the moon is farther from Earth – our planet instead passes through a part of the moon’s shadow called the antumbra, which isn’t quite as dark.

You’ll need special glasses to stare directly at the eclipse

solar eclipse
Children use special glasses to look into the sky during a partial solar eclipse in Madrid, Spain on March 20, 2015.

It’s dangerous to stare directly at any solar eclipse for the same reasons it’s dangerous to look at the sun: The bright light can damage cells in your retina.

This may ultimately distort your vision, resulting in blind spots or trouble making out shapes. Your eyes can also become watery and sore. Sometimes, these side effects won’t show up for a few hours or even a few days.

So if you want to view Thursday’s solar eclipse in person, NASA recommends wearing a pair of “eclipse glasses” with special solar filters. (The American Astronomical Society has a list of reputable manufacturers.) You can also purchase a pair of welder’s goggles in shade 12 or higher.

Sunglasses aren’t a proper substitute – they transmit thousands of times too much sunlight, according to NASA.

The eclipse will also be livestreamed on Thursday for those looking to watch from home.

After this, the next annular solar eclipse won’t happen until October 14, 2023. In the meantime, the world can look forward to December’s total solar eclipse, plus two partial solar eclipses in 2022.

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NASA says a ‘potentially hazardous’ asteroid, which could be bigger than the Eiffel Tower, will shoot past Earth next week

asteroid earth fly by
An artist’s illustration of asteroids flying by Earth.

  • An asteroid possibly bigger than the Eiffel Tower is expected to fly past Earth next week.
  • NASA has classified the huge space rock as “potentially hazardous.”
  • The asteroid will travel at a speed nearly equivalent to 20 times as fast as a rifle bullet.
  • See more stories on Insider’s business page.

An asteroid that could be taller than the Eiffel Tower is expected to shoot past Earth next month.

The mammoth space rock has been classified as “potentially hazardous” by NASA, per Newsweek, though it is expected to pass by safely. NASA usually determines whether an asteroid is possibly hazardous by examining its size and distance from our planet.

Known as 2021 KT1, the asteroid will make a “close approach” to Earth on June 1 at about 10:24 am EDT, according to NASA.

The word “close” is a relative concept in cosmic terms. It is estimated that the distance the rock will actually swing past Earth is around 4.5 million miles. Even though this is roughly 19 times the distance between the Earth and the Moon, NASA still considers the pass in its near approaches datasheet, Newsweek reported.

It will fly past Earth at a speed of roughly 40,000 mph, per NASA. This is 20 times the speed of a rifle bullet, according to Newsweek.

NASA estimates the size of the asteroid to be between 492 feet and 1,082 feet in diameter. This is roughly the size of three NFL football fields combined, according to The Washington Newsday.

But according to the agency’s Center for Near-Earth object Studies, is not a major cause for concern. “No one should be overly concerned about an Earth impact of an asteroid or comet,” it said in a post on its website. “The threat to any one person from auto accidents, disease, other natural disasters and a variety of other problems is much higher than the threat from NEOs.

However, it added that the chances of our planet being hit by an asteroid one day are slim but never zero.

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Earth’s stratosphere has been shrinking for 40 years. That could one day screw with orbiting satellites.

Clouds above earth
A band of subtropical stratocumulus clouds as seen from space.

About 7.5 miles above our heads, the stratosphere begins.

That slice of sky – where supersonic jets and weather balloons fly – stretches up to 31 miles above Earth’s surface. But according to new research, this layer of the atmosphere has shrunk by a quarter-mile in the last 40 years.

A study published last week in the journal Environmental Research Letters shows that humanity’s greenhouse-gas emissions are behind the startling contraction.

As carbon dioxide from the burning of fossil fuels enters the lowest level of the atmosphere – known as the troposphere – it traps some of the sunlight that hits Earth as that light is being reflected back into space. That’s why the planet’s temperature is rising. The more emissions rise, the more heat from the sun stays trapped on Earth and the less it can warm the stratosphere as it travels spaceward. So the stratosphere is cooling.

As the stratosphere cools, it shrinks (as most materials do). Between the 1960s and mid-2010s, it cooled by up to 5 degrees Fahrenheit (3 degrees Celsius). If global greenhouse-gas emissions continue at their current level or increase, that shrinkage is expected to continue.

The new study suggests that the stratosphere will get almost a mile thinner by 2080 – about a 4% decrease from its average thickness between 1980 and 2018.

That thinning could eventually mess with GPS navigational systems, radio communications, or the trajectories of orbiting satellites.

A contracting atmosphere

earth atmosphere
An image taken from the space station shows the limb of the Earth transitioning into the orange-colored stratosphere.

Imagine Earth’s atmosphere as a decadent, layered trifle cake.

The troposphere is closest layer to the planet, a 7.5-mile band where most of our weather happens, and where commercial airplanes fly. It meets the stratosphere above it at a boundary known as the tropopause.

On the stratosphere’s other side is the mesosphere, which extends 50 miles up; the boundary between those two layers is called the stratopause. Then comes the upper atmosphere, reaching 440 miles high. That includes the thermosphere, where satellites and the International Space Station orbit, and the ionosphere.

According to the new study, the boundaries on either side of the stratosphere – the tropopause and the stratopause – are getting to closer to each other, suggesting the stratosphere is being compressed. Since 1980, the altitude of the tropopause has been increasing, and the altitude of the stratopause has the been decreasing. Picture the filling of a whoopie pie gripped too tightly.

That trend, the researchers said, is expected to continue unless carbon emissions are sharply reduced. (Atmospheric carbon-dioxide concentrations hit a record high last year.)

“Carbon dioxide cools the stratosphere, and when the stratosphere cools, it actually shrinks the size of the atmosphere,” Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, told Canada’s National Observer in 2016.

If you’re in the mesosphere about 50 miles up, he added, “you actually are seeing the sky falling – it’s going down by a number of kilometers.”

Bad news for orbiting satellites?

gps block iiia 3a satellite illustration
An illustration of a US military GPS satellite in orbit.

Satellites orbit Earth above the stratosphere, but because any change in one layer of the atmosphere can spell trouble for the others, a contracting stratosphere could impact those satellites.

“If (and it is a big if) the shrinking stratosphere were to lower all the atmospheric layers above it, low-altitude satellites would experience reduced air resistance, which could modify their trajectories,” Paul Williams, a professor of atmospheric science at Reading University in the UK who was not involved in the study, told The Times.

That modification could eventually wreak havoc on GPS satellites or other space-based navigation systems, according to the new study, perhaps making them less accurate.

High-frequency radio transmissions could also get screwed up, since this means of communication involves bouncing radio waves off charged particles in the ionosphere. That’s how airplane pilots talk to air traffic control towers in the northernmost regions of the planet where GPS doesn’t work, like the Arctic.

“Any change to the altitude of the electrically charged layer could alter the transmission of radio waves,” Williams said.

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Sharks are among a group of animals with a 6th sense that humans don’t have – they use Earth’s magnetic field to navigate

bonnetheads sharks
Bryan Keller holding a bonnethead shark.

Shark species have an uncanny ability to find their way back to the same feeding grounds every year – even areas thousands of miles away.

According to a study published Thursday, that’s because sharks have a superior navigational tool at their disposal: They can orient themselves using Earth’s magnetic field.

They’re far from the only animals to do so. Birds, whales, and many other species use the same sixth sense to plot their migrations.

Bryan Keller, a biologist at Florida State University who co-authored the new study, likens this sense to “having an ‘internal GPS.'”

“This is, in my opinion, the best explanation for how migratory sharks successfully navigate during long-distance movements,” Keller told Insider.

‘Sharks garner map-like information from the magnetic field’

Earth's Magnetic Field
An illustration of Earth’s magnetic field.

Nearly 2,000 miles below Earth’s surface, swirling iron in the planet’s outer core conducts electricity that generates a magnetic field. This field stretches all the way from the planet’s interior to the space surrounding the Earth. It’s what protects the world from deadly solar radiation.

But the direction that the electromagnetic energy flows, as well as the strength of the resulting protective sheath, depends on where on the planet’s surface you are. So animals that use the magnetic field to orient themselves do so by detecting these differences in field strength and flow. They then use that information to figure out where they are and where to go.

Scientists long suspected sharks could navigate using the field, since the animals can sense electromagnetic fields in general. But that hypothesis had been difficult to confirm until Keller’s study.

His team examined the bonnethead shark, known as Sphyrna tiburo, because the species exhibits site fidelity – meaning it returns to the same estuary habitats each season.

“This means the sharks have the capability to remember a specific location and to navigate back to it,” he said.

bonnetheads sharks
An overhead shot of bonnethead sharks in a holding tank.

The team captured 20 bonnetheads off the coast of Florida in the Gulf of Mexico, then placed the sharks in a 10-by-10-foot tank. They generated a tiny magnetic field within a 3-square-foot area of that tank. (Bonnetheads only reach 4 feet in length, which made them an ideal species to study in such a small pool, Keller said.)

The team then tweaked that localized magnetic field to mimic the electromagnetic conditions of various locations hundreds of miles away from where they’d caught the sharks. If the animals were truly relying on magnetic-field cues to navigate, the thinking went, then the bonnetheads would try to reorient themselves and start swimming in the direction they thought would lead to the Florida coast. That’s exactly what happened.

When the researchers mimicked the conditions of the magnetic field on Florida’s Gulf Coast, the animals exhibited no preference in which direction they were swimming – suggesting they assumed they were already in the right place.

“I’m not surprised that sharks garner map-like information from the magnetic field, because it makes perfect sense,” Keller said.

Many animals use the magnetic field for navigation

Even though the new study was done on bonnetheads, Keller said the findings likely apply to other shark species as well.

Great White Shark
A great white shark heads near the Neptune Islands, Australia, in June 2014.

How else could a great white, for example, migrate from South Africa to Australia – a distance of more than 12,400 miles – then return to the exact same chunk of ocean nine months later?

“En route to Australia, the animal exhibited an incredibly straight swimming trajectory,” Keller said of great whites. “Given that the magnetic field is perhaps the only constant and ubiquitous cue available to these migratory sharks, it is sensible that magnetic-based navigation is responsible for facilitating these incredible navigational successes.”

Other navigational cues do exist, including currents and tides, but Keller said the magnetic field “is likely more useful than these other aids because it remains relatively constant.”

Biologists still aren’t sure how sharks detect the field, but a 2017 study suggested that the animals’ magnetic receptors are probably located in their noses.

The ability to detect and orient using the magnetic field is fairly common in the animal kingdom overall, according to Keller. Scientists have observed that type of behavior in bacteria, algae, mud snails, lobsters, eels, stingrays, honey bees, mole rats, newts, birds, fish like tuna and salmon, dolphins, and whales.

Sea turtles, too, rely on magnetic cues when they migrate thousands of miles to lay eggs on the same beaches where they hatched.

Two_Wire_Fox_Terriers
Two wire-haired Fox Terriers.

Dogs, meanwhile, can find their way home both using their impressive sense of smell and by orienting themselves using the magnetic field, according to a June study.

“The magnetic field may provide dogs with a ‘universal’ reference frame, which is essential for long-distance navigation,” that study said.

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What if the Earth spun sideways on its axis

Following is a transcript of the video.

Early in the history of our solar system, something mysteriously knocked Earth slightly off its axis. So today we tilt at 23.5 degrees. But what would happen if we tilted even more? What if Earth spun sideways on its axis? Well, it wouldn’t take long before utter chaos ensued.

One of the most important consequences of Earth’s axial tilt is the seasons. Seasons happen because the tilt points different parts of the planet toward the sun at different times of the year. But the tilt also means that different parts of the globe receive different amounts of sunlight during each season. And that’s where a more extreme tilt starts to cause problems. Right now, during the summer in the Northern Hemisphere, places far north, like Utqiagvik, Alaska, receive 24 hours of sunlight for 82 days straight. Because Earth is tilted far enough on its axis that as the planet rotates, Utqiagvik never leaves direct sunlight. On the other hand, the contiguous US receives a max of 17 hours a day, because after that it rotates out of daytime sunlight and into night. But if we tilted Earth’s axis even more, to 90 degrees, the US would get sunlight 24/7, around the clock, for months on end. And it’s not just the US; the entire Northern Hemisphere would be like this.

At first, animals would take advantage of the extra light to find and eat more food, just like Alaskan birds, which feed their chicks extra nutrition in the summer, resulting in faster-growing babies than their southern counterparts. And plant growth would explode since they get their energy directly from sunlight. Farms in northern Alaska, for example, grow cabbages the size of rottweilers in the summer.

But while animals and plants would thrive, humans wouldn’t. We evolved to be active during the day and sleep at night. But if we were exposed to unending sunlight, our brains would stop producing the hormone melatonin, which we need to sleep at night. And that could lead to sleep deprivation, depression, and, ultimately, a more severe, chronic version of these symptoms called seasonal affective disorder, which already affects 9% of Alaskans, compared to just 6% of the entire United States.

But that’s less of a worry than the floods. Temperatures at the North Pole would more than double, to 38 degrees Celsius from 15.5 degrees Celsius. That’s hotter than temperatures at the equator today. As a result, Greenland’s ice cap would melt, causing sea levels to rise by 7 meters, and flood nearly every coastal city on Earth. Say goodbye to New York, Copenhagen, and Tokyo. To make matters worse, the warmer seas would trigger stronger and more frequent hurricanes, which form when seawater evaporates at the surface.

And the weather wouldn’t get better when winter comes six months later. Out of reach of the sun’s direct beams for months at a time, the hemisphere would get colder than any winter on record. Swirls of frigid air, called a polar vortex, which are normally dissipated by warm air in the tropics, could travel all the way down to the equator. Imagine blizzards in Florida, Brazil, Kenya! And all those thriving plants, they’d die from a lack of sunlight. Agriculture would collapse as ecosystems crumble and mass extinctions pile up.

And there would be even more floods, because meanwhile, the Southern Hemisphere is getting toasty and the South Pole is home to 90% of the world’s ice. The constant sunlight would raise its temperature to 38 degrees Celsius from -28 degrees Celsius, melting the ice and raising sea levels by a whopping 61 meters. That’s almost as tall as the Leaning Tower of Pisa. Greenland’s flood would look like a puddle in comparison.

So all in all, while a few extra hours in the summer sun would be nice, let’s leave the extra seasons to Alaska and be glad the Earth is tilted exactly as it is.

EDITOR’S NOTE: This video was originally published in July 2019.

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An astronomer’s animation shows how Earth and the moon both orbit a spot 3,000 miles from the true center of the planet

globe_epc_2015198_lrg
The Deep Space Climate Observatory (DSCOVR) captured a view of the moon as it passed between the spacecraft and Earth.

The moon orbits Earth – right? The answer is actually a little more complicated than that.

The moon is circling a point about 3,000 miles from our planet’s center, just below its surface. Earth is wobbling around that point, too, making its own circles.

That spot is the Earth-moon system’s center of mass, known as the barycenter. It’s the point of an object (or system of them) at which it can be balanced perfectly, with the mass distributed evenly on all sides.

The Earth-moon barycenter doesn’t line up exactly with our planet’s center. Instead, it’s “always just below Earth’s surface,” as James O’Donoghue, a planetary scientist at the Japanese space agency (JAXA), explained on Twitter.

It’s hard to imagine what that looks like without seeing it for yourself. So O’Donoghue made an animation to demonstrate what’s going on. It shows how Earth and the moon will move over the next three years.

The distance between Earth and the moon is not to scale in the animation, but O’Donoghue used NASA data, so the positions over time are accurate.

“You can pause the animation on the present date to figure out where the Earth and moon physically are right now,” O’Donoghue said.

Every planetary system – including the star or planet that appears to be at the center – orbits an invisible point like this one. Our solar system’s barycenter is sometimes inside the sun, sometimes outside of it. Barycenters can help astronomers find hidden planets circling other stars: A star’s wobbling motion allows scientists to calculate mass they can’t see in a given system.

O’Donoghue made a similar animation of Pluto and its moon, Charon. In this system, the barycenter is always outside of Pluto.

That’s because Charon’s mass is not that much smaller than Pluto’s, so the system’s mass is more evenly distributed than Earth and our moon.

Because the barycenter is outside of Pluto, O’Donoghue said, you could actually consider this to be a “double (dwarf-)planet system” rather than a dwarf planet and its moon.

In his free time, O’Donoghue has also made animations to explain why leap years are necessary, why you’ve probably never seen a model of the solar system to scale, and how incredibly slow the speed of light is.

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An Eiffel Tower-sized asteroid is about to whiz by Earth. When it returns in 8 years, it could cross paths with our satellites.

asteroid earth fly by
An artist’s illustration of asteroids flying by Earth.

  • An asteroid called Apophis, after the ancient Egyptian god of chaos, will fly by Earth Friday night.
  • The space rock is more than 1,100 feet wide — wider than the Eiffel Tower is tall.
  • When Apophis returns in 2029, its path could intersect with high-altitude satellites in Earth’s orbit.
  • Visit the Business section of Insider for more stories.

An asteroid nearly four football fields wide is about to zoom by Earth.

The space rock is named 99942 Apophis, after the ancient Egyptian god of chaos. It’s is wider than the Eiffel Tower is tall: about 1,115 feet (340 meters).

On Friday night at 8:15 p.m. ET, the asteroid will come within 10.4 million miles of Earth’s surface. That’s about 44 times the distance between Earth and the moon. But Apophis’ next close flyby, on April 13, 2029, will bring the asteroid within 19,000 miles of Earth – that’s in between our planet and the moon. It will be the closest any asteroid of Apophis’ size has come to Earth’s surface that scientists have known about in advance, according to NASA

That future approach will even be close enough that the asteroid could collide with high-altitude communications satellites orbiting Earth.

The animation below shows what the distance between Apophis and Earth will be eight years from now. The blue dots represent orbiting satellites, and the International Space Station is in pink.

Preparing for Apophis’ return

Apophis won’t be visible to the naked eye tonight – you’d need a telescope with at least a foot-long diameter to see it. But Rome’s Virtual Telescope Project is offering an online viewing session at 7 p.m. ET.

The asteroid’s discovery made waves in 2004, since astronomers calculated at the time that there was a small chance it could hit the planet in 2029. NASA scientists have since revised that estimate.

“We have known for some time that an impact with Earth is not possible during the 2029 close approach,” Dave Tholen, a researcher at the University of Hawai’i Institute for Astronomy who helped discover Apophis, said in October.

Every time an asteroid nears Earth, it’s a chance for astronomers to study the space rock and learn about its shape and spin.

When scientists first spotted Apophis in June 2004, they had just two days to inspect it before weather and technical issues got in the way. No images exist of the rock’s surface. So this imminent close pass, as well as the one in 2029, will help scientists investigate Apophis’ composition.

“The Apophis close approach in 2029 will be an incredible opportunity for science,” Marina Brozović, a radar scientist at NASA’s Jet Propulsion Laboratory, said in 2019. “We’ll observe the asteroid with both optical and radar telescopes. With radar observations, we might be able to see surface details that are only a few meters in size.”

During that 2029 flyby, Apophis will be visible to the naked eye, appearing as a fast-moving point of light that starts in the night sky over the Southern Hemisphere and moves across the globe from east to west.

The NASA animation below shows Apophis’ path on April 13, 2029.

 

Apophis has a 1 in 380,000 chance of striking Earth in 2068

Apophis originated from the asteroid belt between Mars and Jupiter. So far, NASA knows it is made up of silicate rocks, nickel, and iron. Radar images suggest it looks like a peanut.

After 2029, Apophis will have more near-Earth encounters, passing by again in 2036 and 2068. There’s no chance of an impact in 2036, but NASA calculations suggest a 1 in 380,000 chance that Apophis could strike in 2068.

Until last year, astronomers thought it was impossible that Apophis would strike Earth in 2068, but that changed after Tholen’s team presented new research at the annual meeting of the American Astronomical Society. The group showed the asteroid was changing speed and direction over time.

asteroid vesta
The asteroid Vesta in space.

These changes come from a process known as Yarkovsky acceleration: As asteroids absorb energy from the sun, they radiate the energy out as heat, which slightly changes their orbital paths.

The recent research found that this is happening to Apophis.

The asteroid’s orbit is shifting by about 558 feet per year, Tholen said – which is “enough to keep the 2068 impact scenario in play.”

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What Elon Musk’s 42,000 Starlink satellites could do for – and to – planet Earth

  • Over the next few decades, Elon Musk is hoping to send 42,000 satellites to space.
  • He is hoping those satellites bring high-speed internet to every corner of the world— from the rainforest to Antarctica.
  • But experts worry that the number of satellites could have a major impact on our planet.
  • Their bright reflections are already blocking the views of astronomers looking for deadly asteroids. If enough of them become disabled, which is already happening, they could also block off space travel for decades.
  • Visit Business Insider’s homepage for more stories.

Following is a transcript of the video.

You’re looking at 60 satellites hurtling into the sky. And over the next few decades, Elon Musk is hoping to send 42,000 of these satellites to space, 15 times the number of operational satellites in orbit today. It’s part of Starlink, the expansive constellation from Musk and SpaceX that hopes to bring the world low-latency high-speed internet, promising no more buffering and nearly instantaneous internet in every corner of the world. But experts worry it may come at a hefty cost for space exploration.

Nearly half of the world’s population does not have access to the internet, because most internet options require an extensive track of costly underground cables, leaving many rural locations offline. And while satellite internet can reach those areas…

Dave Mosher: Traditional satellite internet is provided by a bus-sized spacecraft that is launched 22,236 miles into space in orbit around Earth.

Narrator: That distance means the satellite can reach places that cables can’t. But since that one satellite is meant to service a lot of people, its data capability is limited, which then limits connection speeds. And that signal has to travel a long way, creating a lot of lag. This is where Elon Musk and SpaceX come in.

Mosher: Starlink is a globe-encircling network of internet-beaming satellites that is trying to get you online no matter where you are in the world.

Narrator: And there’s a rather persuading element for SpaceX as well.

Mosher: Elon Musk has said he’s just trying to grab a small percentage of a trillion-dollar-a-year telecommunications industry around the world. If SpaceX can pull this off, the company could net about $30 to $50 billion a year.

Narrator: Musk and SpaceX president Gwynne Shotwell say that much money could single-handedly fund the development of Starlink, Starship, and SpaceX’s Mars-launch infrastructure. As of early October, SpaceX has launched more than 700 satellites into orbit, with a plan to release a total of 12,000 over the next five years, half of them by the end of 2024. And Musk wants to add another 30,000 to that, coming to a total of 42,000 satellites circling Earth. All of these satellites will also be much closer, anywhere from 200 to 400 miles above the planet in low-Earth orbit.

Mosher: This reduces the connection delay that is found with traditional internet satellite.

Narrator: Once in orbit, these Starlink satellites will be constantly on the move, which is why so many are necessary.

Mosher: The problem is you have to have many satellites orbiting to make up for the fact that you can’t stay in one spot above the Earth. Because you need several satellites overhead at any one time to cover many users.

Narrator: Every satellite will connect with several others via laser beams, creating something like the network’s backbone. And to actually bring this internet into your home, you’ll need to get a pizza-sized antenna. This phased-array antenna can aim its beam at whatever satellite is overhead, which will maintain an internet signal in your home. But this scheme isn’t without problems. Starlink satellites are bright. They reflect the sunlight and shine it back towards Earth, so they end up looking like bright moving stars. As cool as it may look, that comes with problems.

Mosher: Starlink satellites are most visible in the night sky right before dawn and right after dusk, which is the exact time that astronomers are hunting for near-Earth objects or asteroids, objects that could hit Earth and possibly harm us.

Narrator: And as more satellites go up, so does the likelihood that they’ll interfere with astronomers’ views. Mosher: If Starlink continues to be a problem for these type of sky surveys, we may not have as much notice as we want to detect a near-Earth object and thwart it and prevent it from hitting Earth.

Narrator: Beyond detecting deadly asteroids, the wall of satellites could also obstruct the search for new planets or even black holes.

Mosher: SpaceX realized it had to do something, and it did. It created what’s called a DarkSat, which is a satellite that has all of its shiny parts coated in a very black, dark material.

Narrator: It also tried adding visors to shield those shiny parts from the ground. But unless the satellites are cloaked like a spaceship in “Star Trek,” technology that does not exist, none of this will fully solve the problem. And even if it did, there is a much bigger issue at hand.

Mosher: There’s a concern about space debris, because when you have so many satellites in the closest, tightest, densest orbits around Earth, there’s a higher chance that those satellites could collide with each other or with other satellites.

Narrator: Those crashes would create clouds of debris that can orbit the Earth for years, decades, or even centuries.

Mosher: And that debris can then disable or cause other satellites to crash into each other, creating even more debris, and this problem spirals out of control in an effect called the Kessler syndrome. And if we reach that, then essentially space is too unsafe to access.

Narrator: To be clear, the risk of a runaway Kessler syndrome is very low.

Mosher: But the potential impacts of that are so high that scientists are working very hard to control such an event from ever happening.

Narrator: SpaceX has said its satellites can automatically move out of the way to avoid collisions. But dozens of SpaceX satellites are already disabled and can’t move at all, posing a potential threat. And those concerned with SpaceX’s plans are lobbying the FCC to rein in the company and more strictly regulate low-Earth orbit. And that could make it more expensive and harder to deploy the planned 42,000 satellites. But it doesn’t stop at Starlink.

Amazon’s Kuiper project, OneWeb, China’s Hongyan, and other projects are looking to challenge SpaceX by launching their own global networks of hundreds or thousands of satellites. If they all got their way with little to no regulation, we could end up with 100,000 satellites encasing our planet within the next 10 years, dramatically increasing the risk of blocking off space for everyone.

EDITOR’S NOTE: This video was originally published in October 2020. 

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