The new moon of August comes on Saturday the 11th this year, perfectly timed to bring dark, moonless nights around the peak of the Perseid meteor shower. Indeed, 2018 is an excellent year to watch for these meteors; such moonless-sky conditions are ideal for observing the Perseids.
Moreover, Earth should pass through the shower's richest part around 9 p.m. Eastern time on Sunday, Aug. 12 (0100 GMT on Aug. 13).
So, late that night into the predawn hours of Monday, Aug. 13, viewers in North America and Europe should have the best seats in the house. Late-summer campers should put their sleeping bags outside the tent to enjoy this "Old Faithful" of meteor showers. [Perseid Meteor Shower 2018: When, Where & How to See It]
The Perseids no longer hold the title of the "most prolific" of the annual meteor displays; the December Geminids now produce meteors in greater numbers. But the Perseids are still the most popular because they appear during balmy summer nights as opposed to the wintry Geminids.
Of course, the Perseids are not stars dropping from their fixed positions in the sky. Rather, they are tiny flecks of material that were shed by Comet Swift-Tuttle each time it swept past the sun. While meteors can be seen on any given night, the majority of meteors that are seen in mid-August skies belong to the Perseid stream. (See a visualization of the Perseids here.)
Comet Swift-Tuttle was discovered during the summer of 1862 by Lewis Swift, an amateur astronomer based in New York; and Horace Tuttle, a professional astronomer at the Harvard College Observatory. The comet has an orbital period of roughly 130 years and was last sighted in December 1992. Its next expected return is slated for August 2126.
The comet has likely circled the sun many hundreds of times and has left a "river of rubble" in its wake. Because the respective orbits of Earth and Comet Swift-Tuttle nearly coincide in the middle of August, Earth ends up sweeping through this rubble river. As we plow through the debris field, these tiny pieces of comet dust ram through the upper atmosphere at 37 miles per second (60 kilometers per second). Friction with the atmosphere raises these particles to white heat and produces an incandescent trail of ionized gas, which dleads to tt the "shooting star" effect.
As with all meteor showers, the Perseids will appear to diverge from a small spot ind the sky, called the "radiant" — in this case, it's the northern part of the constellation Perseus, located not far from its famous Double Cluster (hence the name "Perseids"). For much of the United States, the radiant is already above the northeast horizon as darkness is falling. If you're lucky, you might catch sight of a few Perseids as early as 9 or 10 in the evening. These forerunners stand out from the meteors later in the night because they produce long, bright paths across the greater part of the sky.
Such meteors are called "Earth skimmers" and often leave long-lasting trains in their wake. Earth skimmers are very distinctive because they follow a path nearly parallel to our planet's atmosphere, but during the evening hours, they tend to be few and far between. But after the stroke of midnight, meteor activity begins to noticeably ramp up because we're on the forward-moving side of Earth and are ramming straight into the Perseid stream. Meteor activity also picks up around this time because the radiant is climbing higher in the sky; from midnight until the first light of dawn, meteors may appear at rates of 60 to 90 per hour, and this frequency is another reason this display is so popular.
If, however, you live in a brightly lit city surrounded by obstructions such as tall buildings, you will see considerably fewer meteors. When I was a young boy living in the Throggs Neck section of the Bronx, I would watch for the Perseids from my backyard. My view of the sky was quite limited, and I also had to contend with nearby streetlights — so I usually averaged only about 10 Perseids each hour.
In later years, I did my Perseid watching from my aunt and uncle's house in Mahopac, New York, 55 miles (88 km) north of Midtown Manhattan, which, in those days (the early 1970s), was a very dark, rural location. When I watched from the south-facing deck of the house, my hourly meteor counts were much higher, on the order of 40 or 50. If I had positioned myself toward a different location where I could see more of the sky, I probably could have seen even more meteors. [Top 10 Perseid Meteor Shower Facts]
Great balls of fire!
It's not just the quantity, but the quality, of meteors that makes the Perseids so popular. Many of the meteors you will see are swift and rather bright, in the average magnitude range of 2 to 2.5, or about the brightness of Polaris (the North Star) or the brightest stars of the Big Dipper. The brighter streaks are usually tinged with a bluish or greenish hue, while fainter meteors tend to appear yellow or white.
About one-third of all Perseids leave luminous trains, which can persist from a few seconds to nearly a minute. Such outstandingly bright meteors are called fireballs. And according to Bill Cooke of NASA's Meteoroid Environment Office, the Perseids produce more fireballs than any other meteor shower. A few might end in flares or bursts resembling a strobe, capable of casting shadows. Such meteors are called "bolides."
If you have binoculars, you can prolong a meteor train's visibility. It's a fascinating sight to watch a meteor streak that starts off straight and true and within just a few seconds appears to twist and turn as it responds to high-level winds in Earth's upper atmosphere at altitudes of 40 to 50 miles (65 to 80 km).
One of the brightest Perseids I ever saw occurred back in August 1974, when I was observing the shower from the southern Adirondack Mountains with several members of the Amateur Observers' Society of New York. Here is my report, which appeared in the October 1974 issue of Astronomy magazine (page 39):
"I looked down at my tape recorder planning to insert a fresh cartridge, when it suddenly became illuminated by something which I thought at first was the dull light of one of my colleagues' heavily filtered flashlights. I instinctively looked up and was stunned by a great fireball in its final stage, moving almost due south into northern Sagittarius. The light emitted by this Perseid was intensely green and was estimated to be at least magnitude -10 (about the brightness of a first or last quarter moon)." [Photograph the 2018 Perseid Meteor Shower with These NASA Tips]
The best piece of equipment for meteor watching is a long, reclining lawn chair, which you can lie on to get a wide-open view of the sky. If you stand and look upward for a long period of time, there's a fair chance that you'll find yourself nursing a stiff neck the following morning. And even though the calendar says it's midsummer, remaining stationary for a long time while lying down close to the ground can cause you to get chilled — and possibly coated with dew. Be sure to have a heavy blanket — or, better yet, a sleeping bag — on hand to stay warm. Some food and a warm beverage (no alcohol!) will keep you comfortable as well.
And it can be fun to watch for meteors with friends or even just a single companion. When I was watching for Perseids as a boy from the Bronx, my grandmother usually watched with me. We'd also have a radio tuned to a station that played dreamy classical music and popular orchestrations, which served as a fitting accompaniment to the show taking place above our heads.
If you're clouded out of the peak viewing night, don't worry; the Perseids will continue to be evident, albeit in diminished numbers, for almost another two weeks. Hourly rates average about one-half to one-quarter of the peak numbers for a night or two before and after. And the very last stragglers have been noted as late as Aug. 24.
As always, good luck, and here's to clear skies!
Editor's note: If you snap an awesome photo of Perseid meteors that you'd like to share with Space.com and our news partners for a potential story or gallery, send images and comments to firstname.lastname@example.org.
Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers' Almanac and other publications, and he is also an on-camera meteorologist for Verizon FiOS1 News in New York's Lower Hudson Valley. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.
The past four years have been the hottest on record, but new research shows the Earth was actually in a global warming "hiatus" that is about to end. And when it does, natural factors are likely to help an already warming planet get even hotter over the next four years, according to a new forecasting model.
Rising CO2 levels have caused the temperature of the planet to rise, said lead author of the Nature Communications paper, Florian Sevellec, a professor of ocean and Earth science at the University of Southampton in the United Kingdom and a scientist at France's National Centre for Scientific Research.
Records show 2017 marked the 41st consecutive year with global temperatures at least marginally above the 20th century average, with 2016 being the record-holder. And it's likely that global temperatures in 2018 will be another one for the record books.
However, Earth's natural cycles, which include events like El Nino and La Nina, can also influence global temperatures.
And while Earth seems to have been running a fever for almost a decade straight, the natural cycles have been in their "cooling" phase, Sevellec says — and that's about to shift, raising the global temperature further.
"It will be even warmer than the long-term global warming is inducing," Sevellac said.
This cooler phase of the planet's natural variability is responsible for what is often referred to as a global warming "pause" or "hiatus." While the planet continued to warm, it seemed to plateau.
But that had to end sometime.
John Fyfe, senior research scientist at the Canadian Centre for Climate Modelling and Analysis at Environment and Climate Change Canada, says that multiple issues were at play but mainly the natural variability of the planet.
"I'm not at all surprised by the results," Fyfe said of the new study, in which he was not involved. "And the reason for that is that we have gone down this long slowdown period primarily due to internal variability, and the expectation was that we'd come out of it."
With the Earth continuing to warm, the chances increase for events like heat waves. (Yves Herman/Reuters)
Though CO2 levels were still increasing in Earth's atmosphere, natural cycles like the El Nino Southern Oscillation (ENSO) in the Pacific Ocean were cooler than normal and offset rising global temperatures.
But, Sevellac says, "the long-term trend was building up."
This doesn't mean, however, that we can point to a specific area and better forecast, say, heat waves. Instead, this is a global measurement. But with the Earth continuing to warm, the chances increase for these events.
And global warming doesn't mean that every location on the planet warms uniformly — there are some regions that can be colder than normal — nor does it mean that each year is hotter than the previous one. Instead, it's an overall trend that can play out within a decade or more, with the temperature of the entire planet rising over time.
Probability vs. certainty
In order to test the ability to predict future climate outcomes, the model employs a method that looks backward. In this case, it was able to predict with accuracy the climate slowdown that occurred around 1998 and onward to roughly 2014.
But it's important to note that this is a probability, not a certainty.
The model shows a higher temperature than what was predicted based just on the increased CO2: the probability is 58 per cent for global surface air temperature and 75 per cent for sea surface temperatures.
"Because we tested it over the last century, we know that we are accurate for the likelihood," Sevellac says. "But the likelihood doesn't mean it will occur … there exists a small chance of being cold."
There's no telling how long the cycle will last, if it does manifest: it could be five years or 10. But what's important to note, Sevellac says, is that rising CO2 is still the key player in the warming of the planet.
While the study shows that the Earth's natural variability can have an influence in the short term, Sevellac says, "I think it's also a demonstration that global warming will still be there after all this natural variability."
A dream solution is that humans could develop a way to suck as much CO2 from the atmosphere as we release, and combined with greenhouse gas emission reductions, we could slow or reverse the tide of climate change.
Scientists have found a way to rapidly create the mineral magnesite in a lab both inexpensively and potentially at scale. This could be coupled with carbon sequestration, a process in which carbon is injected and stored underground, typically in depleted oil and gas fields. Reducing the concentration of CO2 in the atmosphere can be both a result of reducing input as well as increasing output of carbon dioxide from the atmosphere.
If implemented at scale, the potential for another tool of CO2 removal via magnesite becomes a possibility, removing carbon dioxide from the atmosphere and storing it long-term in the mineral magnesite.
To explain the above equations, carbon dioxide from the atmosphere is injected into water, which is then dissociated to form carbonic acid. From there, elemental magnesium combines with the carbonic acid to form magnesite (MgCO3).
At this time, most carbon capture and storage options are difficult to implement at scale due to high costs and difficulties scaling. With this new method, however, the rate of magnesite formation goes from hundreds to thousands of years in nature to within 72 days in a lab and at low temperatures.
Based on previous studies, magnesite can remove about half its weight in carbon dioxide from the atmosphere. Estimates put our current CO2 emissions at about 40 billion tons per year. That would mean to remove the equivalent amount of carbon emitted per year solely through magnesite formation, 80 billion tons would have to be produced per year. It becomes increasingly apparent that this cannot be the only lever we pull in mitigating climate change.
By speeding up the process, magnesite could be a legitimate resource for removing carbon dioxide from the atmosphere. However, the research is still in an experimental phase and will need to be continually tested before it could ever be implemented at industrial scales. In addition, the process will rely on the current price of carbon and financial incentives to remove carbon from the atmosphere.
New research published by the Royal Tyrrell Museum on Thursday has sunk previous claims that a swimming dinosaur once paddled the rivers of the Earth.
The paper, published in scientific journal PeerJ, uses computer modelling to conclude the Spinosaurus was not adapted to swim as previously thought.
Research published in 2014 by Nizar Ibrahim and others in the journal Science proposed the dinosaur was partly aquatic, meaning it could both swim and walk on land, a first for any dinosaur.
But using different techniques that relied on physics-based testing methods, the Royal Tyrrell Museum’s curator of dinosaurs, Donald Henderson, found that the 95-million-year-old species would not have been able to survive living in water.
Henderson created three-dimensional, digital models of Spinosaurus and other predatory dinosaurs in order to test their centres of mass buoyancy and equilibrium when immersed in water. He also tested the software using models of semi-aquatic animals such as an alligator and emperor penguin, for comparison.
His models showed the Spinosaurus would have been able to float with its head above water and breath freely, just like other dinosaurs analyzed in the study.
But unlike semi-aquatic animals like alligators, which can easily self-right themselves when tipped to the side in water, the Spinosaurus rolled over onto its side when tipped slightly. The finding implied that the dinosaur species would have easily tipped over in water, forcing it to rely on its limbs to constantly maintain an upright position.
Its centre of mass was also found to be close to its hips, between its hind legs, as opposed to the centre of the torso, which had been proposed by Ibrahim’s 2014 research.
Henderson’s model found the Spinosaurus to be unsinkable underwater, something that would have severely limited its ability to hunt aquatic prey. This differentiates it from traits commonly demonstrated by living aquatic birds, reptiles and mammals, which can submerse themselves to pursue prey underwater.
“The combination of mass close to the hips, an inability to sink underwater, and a tendency to roll onto its side unless constantly resisted by limb use, suggest that Spinosaurus was not specialized for a semi-aquatic mode of life,” the researchers stated.
“Spinosaurus may have been specialized for a shoreline or shallow water mode of life, but it would have still have been a competent terrestrial animal,” added Henderson.