Earth’s New Traveling Buddy Is Definitely An Asteroid, Not Space Junk

At the 49th Annual Division for Planetary Sciences Meeting in Provo, Utah, astronomers led by Vishnu Reddy at the University of Arizona confirm true nature of one of Earth’s companions on its journey around the Sun.

Was it a burned-out rocket booster, tumbling along a peculiar near-earth orbit around the sun, and only occasionally getting close enough to be studied with even the largest telescopes?

Not at all, as it turns out. While, based on previous observations, most astronomers had strongly suspected that object (469219) 2016 HO3 was an ordinary asteroid and not space junk, it took a team of astronomers led by Vishnu Reddy, assistant professor at the Lunar and Planetary Laboratory, University of Arizona, working with one of the world’s largest telescopes, the Large Binocular Telescope (LBT), on Mt. Graham in Southeastern Arizona, to learn the true nature of this near-Earth object.

2016 HO3 is a small near-Earth object (NEO) measuring no more than 100 meters (330 feet) across that, while orbiting the Sun, also appears to circle around the Earth as a “quasi-satellite.” Only five quasi-satellites have been discovered so far, but 2016 HO3 is the most stable of them. The provenance of this object is unknown. On timescales of a few centuries, 2016 HO3 remains within 38-100 lunar distances from us.

“While HO3 is close to the Earth, its small size – possibly not larger than 100 feet – makes it challenging target to study, said Reddy. “Our observations show that the HO3 rotates once every 28 minutes and is made of materials similar to asteroids.”

Soon after its discovery in 2016, astronomers were not sure where this object came from, but in a recent presentation at the annual Division for Planetary Sciences Conference of the American Astronomical Society in Provo, Utah, Reddy and his colleagues show that Earth’s new traveling buddy is an asteroid and not space junk. The new observations confirm that 2016 HO3 is a natural object of similar provenance to other small NEOs that zip by the Earth each month.

“In an effort to constrain its rotation period and surface composition, we observed 2016 HO3 on April 14 and 18 with the Large Binocular Telescope and the Discovery Channel Telescope,” Reddy said. “The derived rotation period and the spectrum of emitted light are not uncommon amongst small NEOs, suggesting that 2016 HO3 is a natural object of similar provenance to other small NEOs.”

In their presentation, “Ground-based Characterization of Earth Quasi Satellite (469219) 2016 HO3,” Reddy and his co-authors, Olga Kuhn, Audrey Thirouin, Al Conrad, Renu Malhotra, Juan Sanchez, and Christian Veillet, point out that the light reflected off the surface of 2016 HO3 is similar to meteorites we have on Earth.

One way to visualize HO3’s orbit is by picturing a hula hoop dancer – the sun in this analogy – twirling two hoops around the hips at the same time, ever so slightly out of sync. While it orbits the sun, the object makes yearly loops (link to www.youtube.com/watch?v=zMJc7gmychk ) around the Earth. As a result, the object appears to orbit the Earth, but it is not gravitationally bound to our planet.

“Of the near-Earth objects we know of, these types of objects would be the easiest to reach, so they could potentially make suitable targets for exploration,” said Veillet, director of the LBT Observatory. “With its binocular arrangement of two 8.4-meter mirrors, coupled with a very efficient pair of imagers and spectrographs like MODS, LBT is ideally suited to the characterization of these Earth’s companions.”

A Rare Hurricane Near Europe Turned The Sun Red

At least two people have died after former Hurricane Ophelia hit Ireland’s west coast this morning (Oct. 16) as a post-tropical storm that turned the Sun red as it rose over the UK.

Ophelia made landfall on the southwest Irish coast in the counties of Cork and Kerry with wind gusts as high as 120 mph, the equivalent of category-3 storm. (It was not technically a hurricane because it formed in the Bay of Biscay rather than tropical waters.)

Ophelia’s size, bigger than the island itself, shows the sheer potential for destruction:

Ophelia could still bring hurricane-force winds across Ireland and Britain.

Ophelia tears into Ireland

Ophelia is the most powerful storm ever recorded in the northeastern Atlantic and the worst storm to hit Ireland since Hurricane Debbie in 1961, which killed 15 .

Met Éireann, the Irish weather office, issued a red-wind warning, the highest level available, for the entire country today (Oct. 16), cautioning “There is a danger to life and property.” Schools throughout the country closed.
The Met Office in the UK issued an amber weather warning for Northern Ireland into parts of Wales and Scotland, with gusts up to 80 mph expected.

“Bear in mind that while in some parts of the country the storm is not yet that bad, it is coming your way,” Ireland’s prime minister Leo Varadkar said at a news conference. “This is a national red alert. It applies to all cities, all counties and all areas.”

Officials in County Waterford said a female driver was killed when a tree fell through her windshield. A man in County Tipperary died from a chainsaw injury after trying to clear a fallen tree. About 360,000 people are without power.

The storm is expected to move into Britain late tonight or early tomorrow (Oct. 17). The US National Hurricane Center, which tracks Atlantic storms, expects Ophelia to weaken over the next day and dissipate over Norway tomorrow night.

About that Red Sun

According to BBC weather reporter Simon King, the redness was caused by the remnants of Ophelia dragging tropical air and dust from the Sahara, along with debris from forest fires in Portugal and Spain. The dust scatters the short-wavelength blue light, allowing longer-wavelength red light to shine through, making the Sun appear red.

UPDATE: Hurricane Ophelia Set To Tear Into UK This Weekend

The tail end of Hurricane Ophelia is set to barrel into the UK, lashing it with rain and winds of up to 70mph, forecasters have warned.

The tropical storm was upgraded to hurricane overnight and the remnants of it could reach the UK over the weekend or early next week.

Although Ophelia will not be strong enough to be categorised as a hurricane by the time it reaches Britain, the west of the country can expect gale-force winds.

Its arrival coincides with the 30th anniversary of the Great Storm of 1987, which hit southern England overnight on 15 October.

Forecaster Michael Fish famously told viewers not to worry about the storm, which killed 18 people and caused £1bn worth of damage.

Hurricane Ophelia is unlikely to cause as much damage as the Great Storm of 1987, which is often referred to as “Hurricane Fish”, but there is the possibility of disruptive weather.

Met Office forecaster Alex Burkhill said: “Ophelia became a hurricane overnight and the forecast track takes it eastwards towards Iberia for the weekend.

“After that, indications are that by that point it will then have weakened and be no longer a hurricane or tropical storm, it will be extratropical. But then it will continue its way towards the British Isles, probably reaching us very early next week.”

He added: “It’s definitely something that we are keeping an eye on, for the possibility of some disruptive weather early next week.”

Hurricane Ophelia’s Winds Strengthen To 85 Mph On Slow Trek Toward Ireland

Hurricane Ophelia continued to strengthen late Wednesday (Oct. 11), with winds reaching 85 mph, as the storm continued a slow trek through the eastern Atlantic toward Ireland, according to the National Hurricane Center.

At 10 p.m., Ophelia was located about 745 miles southwest of the Azores and moving northeastward at nearly three mph.

Forecasters expect Ophelia to continue in that general motion Thursday, but called for the storm to speed up while moving toward the northeast Friday.

Slight strengthening is possible over the next day or two, forecasters said.
Late Wednesday, hurricane-force winds extended up to 25 miles from Ophelia’s center and tropical-storm-force winds extended up to 70 miles.

There were no coastal watches or warnings in effect.

New Theory On Why The Sun’s Corona Is Hotter Than Its Surface

A team of researchers from the U.S., Japan and Switzerland has found possible evidence of a source of energy that could be responsible for heating the sun’s corona. In their paper published in the journal Nature Astronomy, the researchers describe studying data from the FOXSI-2 sounding rocket and what it revealed.

One of the interesting problems in space research is explaining why the sun’s atmosphere (its corona) is so much hotter than its surface. The chief problem standing in the way of an answer is the lack of suitable instruments for measuring what occurs on the sun’s surface and its atmosphere. In this new effort, the researchers used data from the FOXSI-2 sounding rocket (a rocket payload carrying seven telescopes designed to study the sun) to test a theory that suggests heat is injected into the atmosphere by multiple tiny explosions (very small solar flares) on the surface of the sun. Such flares are too small to see with most observational equipment, so the idea has remained just a theory. But now, the new data offers some evidence suggesting the theory is correct.

To test the theory, the researchers looked at X-ray emissions from the corona and found some that were very energetic. This is significant, because solar flares emit X-rays. But the team was studying a part of the sun that had no visible solar flares occurring at the time. This, of course, hinted at another source. The research team suggests the only likely source is superheated plasma that could only have occurred due to nanoflares.
The researchers acknowledge that their findings do not yet solve the coronal heating problem, but they believe they might be getting close. They note that much more research is required—next year, they point out, another sounding rocket will be launched with equipment even more sensitive than that used in the last round, offering better detection of faint X-rays. Also, plans are underway to launch a satellite capable of detecting nanoflares. If future tests can clearly identify the source of the X-rays, the coronal problem may soon be resolved.

Abstract

The processes that heat the solar and stellar coronae to several million kelvins, compared with the much cooler photosphere (5,800 K for the Sun), are still not well known1. One proposed mechanism is heating via a large number of small, unresolved, impulsive heating events called nanoflares2. Each event would heat and cool quickly, and the average effect would be a broad range of temperatures including a small amount of extremely hot plasma. However, detecting these faint, hot traces in the presence of brighter, cooler emission is observationally challenging. Here we present hard X-ray data from the second flight of the Focusing Optics X-ray Solar Imager (FOXSI-2), which detected emission above 7 keV from an active region of the Sun with no obvious individual X-ray flare emission. Through differential emission measure computations, we ascribe this emission to plasma heated above 10 MK, providing evidence for the existence of solar nanoflares. The quantitative evaluation of the hot plasma strongly constrains the coronal heating models.

Two Separate Teams Of Astronomers Find Evidence Of Missing Baryonic Matter

Two teams working independently have found evidence of the existence of Baryonic matter—particles that link galaxies together. One team was made of members from the Institute of Space Astrophysics, the other was based out of the University of Edinburgh. Both teams have uploaded a paper describing their work to the arXiv preprint server and both are claiming their findings solve the mystery of where so much of the normal matter—protons, neutrons and electrons—in the universe has been hiding.

Once scientists came up with the Big Bang Theory, a problem immediately arose—after calculating how much normal matter should exist in the universe at this point in time, they found approximately 50 percent of it is missing. Since then, scientists have worked on theories to explain where all that matter was hiding—the prevailing theory suggests that it exists as strands of Baryonic matter floating in the space between galaxies and cannot be seen with conventional instruments—this was the theory both teams in this new effort tested.

To get around the problem of not being able to see the Baryonic matter directly, the researchers considered a phenomenon called the Sunyaev-Zel’dovich effect in which light left over from the Big Bang scatters as it passes through hot gas—it should be measurable in the cosmic microwave background. Both teams used data from the Planck satellite launched two years ago to create a map of where Baryonic matter strands might exist. Each selected a pair of galaxies to study, focusing on the space between them. Then, they stacked data from between the two galaxies to magnify data believed to be from Baryonic matter.

Both teams repeated this process for multiple pairs of galaxies to show that their readings were consistent across multiple test sites—one team tested a million pairs, the other 260,000. Both report finding evidence of the theorized filaments between the galaxies. One group found them to be three times as dense as the mean of observable matter, the other group six times—a difference that was expected, the groups explain, due to differences in distances from the galaxies that were studied.

Both groups claim their findings prove the existence of missing Baryonic matter and thus solve the mystery of where all the unmeasurable matter has been hiding.

A Surprise From the Supervolcano Under Yellowstone

Beneath Yellowstone National Park lies a supervolcano, a behemoth far more powerful than your average volcano. It has the ability to expel more than 1,000 cubic kilometers of rock and ash at once — 250,000 times more material than erupted from Mount St. Helens in 1980, which killed 57 people. That could blanket most of the United States in a thick layer of ash and even plunge the Earth into a volcanic winter.

Yellowstone’s last supereruption occurred 631,000 years ago. And it’s not the planet’s only buried supervolcano. Scientists suspect that a supereruption scars the planet every 100,000 years, causing many to ask when we can next expect such an explosive planet-changing event.

To answer that question, scientists are seeking lessons from Yellowstone’s past. And the results have been surprising. They show that the forces that drive these rare and violent events can move much more rapidly than volcanologists previously anticipated.

The early evidence, presented at a recent volcanology conference, shows that Yellowstone’s most recent supereruption was sparked when new magma moved into the system only decades before the eruption. Previous estimates assumed that the geological process that led to the event took millenniums to occur.

To reach that conclusion, Hannah Shamloo, a graduate student at Arizona State University, and her colleagues spent weeks at Yellowstone’s Lava Creek Tuff — a fossilized ash deposit from its last supereruption. There, they hauled rocks under the heat of the sun to gather samples, occasionally suspending their work when a bison or a bear roamed nearby.

Ms. Shamloo later analyzed trace crystals in the volcanic leftovers, allowing her to pin down changes before the supervolcano’s eruption. Each crystal once resided within the vast, seething ocean of magma deep underground. As the crystals grew outward, layer upon layer, they recorded changes in temperature, pressure and water content beneath the volcano, much like a set of tree rings.

“We expected that there might be processes happening over thousands of years preceding the eruption,” said Christy Till, a geologist at Arizona State, and Ms. Shamloo’s dissertation adviser. Instead, the outer rims of the crystals revealed a clear uptick in temperature and a change in composition that occurred on a rapid time scale. That could mean the supereruption transpired only decades after an injection of fresh magma beneath the volcano.

The time scale is the blink of an eye, geologically speaking. It’s even shorter than a previous study that found that another ancient supervolcano beneath California’s Long Valley caldera awoke hundreds of years before its eruption. As such, scientists are just now starting to realize that the conditions that lead to supereruptions might emerge within a human lifetime.

“It’s shocking how little time is required to take a volcanic system from being quiet and sitting there to the edge of an eruption,” said Ms. Shamloo, though she warned that there’s more work to do before scientists can verify a precise time scale.

Dr. Kari Cooper, a geochemist at the University of California, Davis who was not involved in the research, said Ms. Shamloo and Dr. Till’s research offered more insights into the time frames of supereruptions, although she is not yet convinced that scientists can pin down the precise trigger of the last Yellowstone event. Geologists must now figure out what kick-starts the rapid movements leading up to supereruptions.

“It’s one thing to think about this slow gradual buildup — it’s another thing to think about how you mobilize 1,000 cubic kilometers of magma in a decade,” she said.

As the research advances, scientists hope they will be able to spot future supereruptions in the making. The odds of Yellowstone, or any other supervolcano erupting anytime soon are small. But understanding the largest eruptions can only help scientists better understand, and therefore forecast, the entire spectrum of volcanic eruptions — something that Dr. Cooper thinks will be possible in a matter of decades.