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New 'mini-moon' set to be captured by Earth might just be space junk – CNET
We’ve got one huge moon looming overhead and you might think “that’s enough moons.” But sometimes, Earth gets greedy and starts pulling in small asteroids for extended stays in orbit. The brief visitations by these “mini-moons” are fairly rare, with only two confirmed so far. The most recent came on Feb. 15, when tiny rock 2020 CD3 wasat the NASA-funded Catalina Sky Survey. had been ensnared by the Earth’s gravity as early as 2015 and stayed with us until May 2020 before dashing off into the cosmos again.
But in the unprecedented year of 2020, astronomers have announced the detection of another potential mini-moon: 2020 SO.
Except this one isn’t acting at all like a small asteroid would. Our mini-moon is no moon at all. It’s moving far too slowly for it to be rock ejected from a cosmic body. Therefore, astronomers reason, it’s probably just space junk left over from the early days of the Space Race.
The current theory holds that 2020 SO is the rocket body from an Atlas Centaur-D rocket originally launched in 1966. The rocket lifted off Sept. 20 carrying the Surveyor 2 lunar lander to the moon. The dimensions and the orbit of 2020 SO, published by NASA’s Jet Propulsion Laboratory, seem to align neatly with the Centaur body.
The object will be grabbed by Earth’s gravitational pull in October and will have its closest approach on Dec. 1, getting to within around 31,000 miles. Astronomers should be able to get a closer look at the object, assessing its shape and the kind of light its emitting.
If it is the Centaur stage — if it is junk — it’s still interesting junk. It’s been out, wandering the solar system for over five decades. We might be able to learn a little about the effects of space on our old rocket bodies. And while it’s not going to cause any problems for Earthlings, as far as we can tell, it does serve as a timely.
Since we first began launching rockets and satellites into orbit, we’ve been polluting space around our planet. Not everything that goes up immediately comes down. There are thousands of pieces of space junk, defunct satellites and tiny chunks of garbage, circling the Earth at great speeds. A collision with a piece of junk could be devastating, blowing a hole right through a rocket or satellite. More launches mean more junk and more junk poses a much bigger risk to spaceflight, satellites and our desire to occupy space.
You don’t even have to look back more than 24 hours to see how the potential issues space debris poses. On Tuesday,to avoid an unknown piece of cosmic trash hurtling toward it.
Arctic summer sea ice 2nd lowest on record, but why care? | Daily Sabah – Daily Sabah
United States government scientists reported Monday that the Arctic Ocean’s floating ice cover has shriveled to its second-lowest extent since satellite records began in 1979.
Until this month, only once in the last 42 years has Earth’s frozen skull cap covered less than 4 million square kilometers (1.5 million square miles).
The trend line is clear: The extent of sea ice has diminished 14% per decade over that period. The Arctic could see its first ice-free summer as early as 2035, researchers reported in the Nature Climate Change journal last month.
But all that melting ice and snow does not directly boost sea levels any more than melted ice cubes make a glass of water overflow, which gives rise to an awkward question: Who cares?
Granted, this would be bad news for polar bears, which are already on a glide path toward extinction, according to a recent study.
And yes, it would certainly mean a profound shift in the region’s marine ecosystems, from phytoplankton to whales.
But if our bottom-line concern is the impact on humanity, one might legitimately ask, “So what?”
As it turns out, there are several reasons to be worried about the knock-on consequences of dwindling Arctic sea ice.
Perhaps the most basic point to make, scientists say, is that a shrinking ice cap is not just a symptom of global warming but a driver as well.
“Sea ice removal exposes dark ocean, which creates a powerful feedback mechanism,” Marco Tedesco, a geophysicist at Columbia University’s Earth Institute, told Agence France-Presse (AFP).
Freshly fallen snow reflects 80% of the Sun’s radiative force back into space. But when that mirror-like surface is replaced by deep blue water, about the same percentage of Earth-heating energy is absorbed instead.
And we’re not talking about a postage stamp area here: The difference between the average ice cap minimum from 1979 to 1990 and the low point reported today – more than 3 million square kilometers – is twice the size of France, Germany and Spain combined.
The oceans have already soaked up 90% of the excess heat generated by manmade greenhouse gases but at a terrible cost, including altered chemistry, massive marine heat waves and dying coral reefs. And at some point, scientists warn, that liquid heat sponge may simply become saturated.
Altering ocean currents
Earth’s complex climate system includes interlocking ocean currents driven by wind, tides and something called the thermohaline circulation, which is itself powered by changes in temperature (“thermo”) and salt concentration (“haline”).
Even small changes in this Great Ocean Conveyor Belt, which moves between poles and across all three major oceans, can have devastating climate impacts.
Nearly 13,000 years ago, for example, as Earth was transitioning out of an ice age into the interglacial period that allowed our species to thrive, global temperatures abruptly plunged several degrees Celsius. They jumped back up again about 1,000 years later.
Geological evidence suggests a slowdown in the thermohaline circulation caused by a massive and rapid influx of cold freshwater from the Artic region was partly to blame.
“The freshwater from melting sea ice and grounded ice in Greenland perturbs and weakens the Gulf Stream,” part of the conveyor belt flowing in the Atlantic, said Xavier Fettweis, a research associate at the University of Liege in Belgium.
“This is what allows western Europe to have a temperate climate compared to the same latitude in North America,” he said.
The massive ice sheet atop Greenland’s landmass saw a net loss of more than half-a-trillion tons last year, all of it flowing into the sea. Unlike sea ice, which does not increase sea levels when it melts, runoff from Greenland does.
That record amount was due in part to warmer air temperatures, which have risen twice as fast in the Arctic as for the planet as a whole. But it was also caused by a change in weather patterns, notably an increase in sunny summer days.
“Some studies suggest that this increase in anticyclonic conditions in the Arctic in summer results in part from the minimum sea ice extent,” Fettweis told AFP.
Bears on thin ice
The current trajectory of climate change and the advent of ice-free summers – defined by the U.N.’s IPCC climate science panel as under 1 million square kilometers – would indeed starve polar bears into extinction by the century’s end, according to a July study in the journal Nature.
“Human-caused global warming means that polar bears have less and less sea ice to hunt on in the summer months,” Steven Amstrup, lead author of the study and chief scientist of Polar Bears International, told AFP.
“The ultimate trajectory of polar bears with unabated greenhouse gas emissions is disappearance,” he said.
If dark matter is a particle, it should get inside red giant stars and change the way they behave – Universe Today
Dark matter makes up the vast majority of matter in the universe, but we can’t see it. At least, not directly. Whatever the dark matter is, it must interact with everything else in the universe through gravity, and astronomers have found that if too much dark matter collects inside of red giant stars, it can potentially cut their lifetimes in half.
When stars like our sun near the end of their lives, they stop fusing hydrogen in their cores. Instead, the fusion takes place in a shell surrounding a dense core of inert helium – the leftover ash from that nuclear reaction. Over the course of hundreds of millions of years, that core contracts (after all, there’s nothing inside of it generating energy to keep it inflated), heating it up.
Simultaneously, because of the increased core temperature, the rest of the star swells, ballooning to ridiculous proportions as a red giant star.
Astronomers can estimate the lifetimes of red giant stars by studying the complex physics of the core, tracing how long the helium can continue to heat until it reaches the critical threshold needed for it to undergo its own nuclear fusion, triggering the final end stages of the star.
It’s a pretty straightforward astrophysical calculation.
That is, it’s pretty straightforward unless something jams up the works.
A Dark Heart
Completely unrelated to red giants, astronomers are currently puzzling over the nature of dark matter, a substance that comprises roughly 80% of all the matter in the universe, yet is completely invisible. We’re not exactly sure what dark matter is, but we’re pretty confident that it is some sort of particle, as yet completely unknown to the standard model of particle physics.
Whatever the dark matter is made of, it must interact with normal matter through gravity, because that’s how we’ve been able to detect it so far. Beyond that, it may be possible for dark matter to form clumps, or regions of high density inside normal-matter objects like stars and planets.
Astronomers have already investigated the consequences of pooling dark matter into the hearts of normal stars, but new research has revealed what happens to red giant stars near the end of their lives.
Short version: it’s not pretty.
According to a paper recently appearing on the preprint journal arXiv, When too much dark matter sits inside a giant star, it causes the helium core to contract more than it normally would. That increased density raises the temperatures, which in turn raises the luminosity, which goes on to make the future evolution of the star that much shorter.
The effects are dramatic. If dark matter makes up a mere 10% of the mass of the red giant core, the temperatures jump by 10%, the luminosity doubles, and the lifetime of the red giant is cut in half.
We don’t know how much dark matter – if any – sits inside red giants, but future studies of this population of dying stars may reveal clues to one of the most enigmatic substances in the universe.
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