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Flying Telescopes Will Watch the Total Solar Eclipse from the Air

If you've ever stood on the tips of your toes to reach something on a high shelf, you get it: Sometimes a little extra height makes all the difference. Although in this case, we're talking miles, not inches, as scientists are sending telescopes up on airplanes to monitor conditions on the Sun and Mercury during the upcoming total eclipse.

Weather permitting, the Great American Eclipse (as some are calling it) will be at least partially visible from anywhere in the continental U.S. on August 21. It will be the first time an eclipse has been so widely visible in the U.S. since 1918 and represents an incredible opportunity not only for amateur sky-watchers but also for scientists from coast to coast.

But why settle for gawking from the ground when there's an even better view up in the sky?

Scientists at the Southwest Research Institute (SwRI) have announced plans to mount monitoring equipment on NASA research planes. The telescopes, which contain super-sensitive, high-speed, and infrared cameras, will rise 50,000 feet (about 9.5 miles) above the Earth's surface to sneak a very special peek at the goings-on in our Sun and its nearest planetary buddy.

Gaining altitude will not only bring the instruments closer to their targets but should also help them avoid the meteorological chaos down below.

"Being above the weather guarantees perfect observing conditions, while being above more than 90 percent of Earth's atmosphere gives us much better image quality than on the ground," SwRI co-investigator Constantine Tsang said in a statement. "This mobile platform also allows us to chase the eclipse shadow, giving us over seven minutes of totality between the two planes, compared to just two minutes and 40 seconds for a stationary observer on the ground."

The darkness of that shadow will blot out much of the Sun's overpowering daily brightness, giving researchers a glimpse at rarely seen solar emissions.

"By looking for high-speed motion in the solar corona, we hope to understand what makes it so hot," senior investigator Amir Caspi said. "It's millions of degrees Celsius—hundreds of times hotter than the visible surface below. In addition, the corona is one of the major sources of electromagnetic storms here at Earth. These phenomena damage satellites, cause power grid blackouts, and disrupt communication and GPS signals, so it's important to better understand them."

The temporary blackout will also create fine conditions for peeping at Mercury's night side. Tsang says, "How the temperature changes across the surface gives us information about the thermophysical properties of Mercury's soil, down to depths of about a few centimeters—something that has never been measured before."

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Space
What Solar Eclipses Look Like on Different Planets
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Triple solar eclipse on Jupiter.

On Monday, August 21, North America will be treated to dazzling views of a total solar eclipse. But what if humans lived someplace else in the solar system—would eclipses be regarded with the same excitement and awe as they are here on Earth?

In her new video, Physics Girl Dianna Cowern investigates what these celestial events look like beyond our home planet. She discovers that, on some planets, total solar eclipses aren't even possible. The two moons orbiting Mars, for example, are too small to completely block the Sun. Move on to other parts of the solar system and you'll find places where total eclipses aren't rare at all. On Jupiter, which has 69 moons, it's possible for there to be multiple eclipses occurring at the same time. On Pluto, whose moon appears much larger in its sky than the Sun, total eclipses can happen every day for years on end.

Considering all the factors required to make a perfect solar eclipse, we're pretty lucky to be able to see one from Earth at all. And if you're close enough to the path of totality to view this year's North American eclipse, you can consider yourself even luckier.

[h/t Physics Girl]

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Big Questions
What is Mercury in Retrograde, and Why Do We Blame Things On It?
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Mercury passing the Sun.

Crashed computers, missed flights, tensions in your workplace—a person who subscribes to astrology would tell you to expect all this chaos and more when Mercury starts retrograding for the third time this year on Sunday, August 13 (or August 12, depending on where you live). But according to an astronomer, this common celestial phenomenon is no reason to stay cooped up at home for weeks at a time.

"We don't know of any physical mechanism that would cause things like power outages or personality changes in people," Dr. Mark Hammergren, an astronomer at Chicago's Adler Planetarium, tells Mental Floss. So if Mercury doesn’t throw business dealings and relationships out of whack when it appears to change direction in the sky, why are so many people convinced that it does?

THE HISTORY

Mercury retrograde—as it's technically called—was being written about in astrology circles as far back as the mid-18th century. The event was noted in British agricultural almanacs of the time, which farmers would read to sync their planting schedules to the patterns of the stars. During the spiritualism craze of the Victorian era, interest in astrology boomed, with many believing that the stars affected the Earth in a variety of (often inconvenient) ways. Late 19th-century publications like The Astrologer’s Magazine and The Science of the Stars connected Mercury retrograde with heavy rainfall. Characterizations of the happening as an "ill omen" also appeared in a handful of articles during that period, but its association with outright disaster wasn’t as prevalent then as it is today.

While other spiritualist hobbies like séances and crystal gazing gradually faded, astrology grew even more popular. By the 1970s, horoscopes were a newspaper mainstay and Mercury retrograde was a recurring player. Because the Roman god Mercury was said to govern travel, commerce, financial wealth, and communication, in astrological circles, Mercury the planet became linked to those matters as well.

"Don’t start anything when Mercury is retrograde," an April 1979 issue of The Baltimore Sun instructed its readers. "A large communications organization notes that magnetic storms, disrupting messages, are prolonged when Mercury appears to be going backwards. Mercury, of course, is the planet associated with communication." The power attributed to the event has become so overblown that today it's blamed for everything from digestive problems to broken washing machines.

WHAT IS IT ACTUALLY?

Though hysteria around Mercury retrograde is stronger than ever, there's still zero evidence that it's something we should worry about. Even the flimsiest explanations, like the idea that the gravitational pull from Mercury influences the water in our bodies in the same way that the moon controls the tides, are easily deflated by science. "A car 20 feet away from you will exert a stronger pull of gravity than the planet Mercury does," Dr. Hammergren says.

To understand how little Mercury retrograde impacts life on Earth, it helps to learn the physical process behind the phenomenon. When the planet nearest to the Sun is retrograde, it appears to move "backwards" (east to west rather than west to east) across the sky. This apparent reversal in Mercury's orbit is actually just an illusion to the people viewing it from Earth. Picture Mercury and Earth circling the Sun like cars on a racetrack. A year on Mercury is shorter than a year on Earth (88 Earth days compared to 365), which means Mercury experiences four years in the time it takes us to finish one solar loop.

When the planets are next to one another on the same side of the Sun, Mercury looks like it's moving east to those of us on Earth. But when Mercury overtakes Earth and continues its orbit, its straight trajectory seems to change course. According to Dr. Hammergren, it's just a trick of perspective. "Same thing if you were passing a car on a highway, maybe going a little bit faster than they are," he says. "They're not really going backwards, they just appear to be going backwards relative to your motion."

Embedded from GIFY

Earth's orbit isn't identical to that of any other planet in the solar system, which means that all the planets appear to move backwards at varying points in time. Planets farther from the Sun than Earth have even more noticeable retrograde patterns because they're visible at night. But thanks to astrology, it's Mercury's retrograde motion that incites dread every few months.

Dr. Hammergren blames the superstition attached to Mercury, and astrology as a whole, on confirmation bias: "[Believers] will say, 'Aha! See, there's a shake-up in my workplace because Mercury's retrograde.'" He urges people to review the past year and see if the periods of their lives when Mercury was retrograde were especially catastrophic. They'll likely find that misinterpreted messages and technical problems are fairly common throughout the year. But as Dr. Hammergren says, when things go wrong and Mercury isn't retrograde, "we don't get that hashtag. It's called Monday."

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