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You Can See a Rare Total Eclipse of a Red Super Harvest Moon

NASA 

On Sunday September 27, something rare and wonderful will happen: the Moon will be full, it will be as near to us as it gets, and it will line up perfectly with the Earth and Sun. The result will be a rare total super harvest moon eclipse, when a giant, full Moon will turn a stunning shade of red.

In celestial terms, that's like a Super Bowl played by Academy Award nominees, with the winner revealing who killed Laura Palmer. It's the only one in a 51-year period; the last supermoon eclipse occurred in 1982, and the next won't come around until 2033. Don't miss it or you'll have to wait 18 years.

WHAT IS GOING ON UP THERE?

We've known for at least 2500 years what a lunar eclipse is thanks to Anaxagoras, a Greek philosopher, who worked out the mechanics in the 5th century BCE. Though we've been recording eclipses for millennia, they never fail to inspire a sense of awe and wonder.

So how does this rare total super harvest moon eclipse come about? You've probably noticed that the Moon appears to be different sizes at various points throughout the year. This is because the Moon's orbit around the Earth is not circular but elliptical. When the Moon is nearest to the Earth on its orbit, it is at "perigee." When it is farthest away, it is at "apogee." At perigee, the Moon appears giant, and at apogee, small.

Note that this is unrelated to the Moon's phases, which are determined by the relative positions of the Sun, Earth, and Moon. For example, when the Earth is between the Moon and the Sun, you see a full moon, because we're looking at the fully sunlit side of the Moon. The three bodies rarely line up exactly, but when they do, you get a total lunar eclipse.

Bringing the two concepts together: When the Moon's phase is full and it is at perigee (i.e. closest to the Earth, and thus giant), you get what astronomers call perigee-syzygy, or, colloquially, a "supermoon." Now add the date to the equation: September is harvest time for farmers, making a full moon that month a "harvest moon." Why? In the days before light bulbs, farmers could use this extra moonlight to harvest crops late into the night.

This weekend the Moon will be full, it will be at perigee, and it will line up perfectly with the Earth and Sun. Because all of this is happening in late September, you get a total super harvest moon eclipse! It's like a moon named by the people who make sequels to Street Fighter.

WHEN TO LOOK UP

On September 27 at 9:07 p.m. EST, the Moon will begin traveling through the Earth's shadow. At 10:11 p.m., the Moon will be fully eclipsed, and will turn an amazing shade of red. The show will last 72 minutes.

But why will it be red? From the vantage point of the Moon, the Earth will appear to be moving across the Sun. Once the Earth is directly between the Moon and the Sun, as NASA evocatively explains, "the darkened terrestrial disk is ringed by every sunrise and every sunset in the world, all at once." The copper sky filters into the shadow of the Earth and is projected onto the white disk that is the Moon. Here's a shockingly crimson Moon as seen from Australia in August 2007.

Image credit: Martin Pugh via NASA
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Space
New NASA Satellite Called TESS Could Discover Thousands of New Planets

Since NASA’s Kepler spacecraft launched in 2009, the space agency has found and confirmed a whopping 2343 new planets. Of those, 30 are considered to be situated in a “habitable zone,” an area in which a planet’s surface could theoretically contain water.

A new satellite, set to launch today, is expected to find thousands more planets outside of our solar system, known as exoplanets. TESS, short for the Transiting Exoplanet Survey Satellite, is NASA’s latest effort to plumb the depths and darkness of outer space in search of other Earth-like planets—including those that could potentially support life.

TESS is slated to complete a two-year survey of the “solar neighborhood,” a general region which comprises more than 200,000 of the brightest nearby stars. To find these outlier planets, NASA scientists will be keeping an eye out for temporary changes in brightness, which indicate that a planet is blocking its host star.

According to Martin Still, the program scientist working on the TESS mission, the launch comes “with certainty” that TESS will find many nearby exoplanets. "We expect to find a whole range of planet sizes, between planets the size of Mercury or even the Moon—our Moon—to planets the same size as Jupiter and everything in between,” Still said in a NASA interview.

While the Kepler mission was considered a major success, NASA noted that most of the planets it recorded are those that orbit faint, faraway stars, making it difficult to conduct follow-up observations. The stars that TESS plans to survey will be 30 to 100 times brighter than those observed by its predecessor. This allows for newly detected planets and their atmospheres to be characterized more easily.

“Before Kepler launched, we didn't know for sure if Earth-sized planets existed,” Elisa V. Quintana, a NASA astrophysicist, told Reddit. “Kepler was a statistical survey that looked at a small patch of sky for four years and taught us that Earths are everywhere. TESS is building on Kepler in the sense that TESS wants to find more small planets but ones that orbit nearby, bright stars. These types of planets that are close to us are much more easy to study, and we can measure their masses from telescopes here on Earth.”

The most common categories of exoplanets are Earth- and Super Earth–sized masses—the latter of which are larger than Earth but smaller than Uranus and Neptune.

TESS is scheduled to launch from the Cape Canaveral Air Force Station in Florida on a SpaceX Falcon 9 rocket at 6:32pm EDT today.

For more information about TESS, check out this video from NASA.

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J. Malcolm Greany, Wikimedia Commons // Public Domain
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Art
An Astronomer Solves a 70-Year-Old Ansel Adams Mystery
Ansel Adams circa 1950
Ansel Adams circa 1950
J. Malcolm Greany, Wikimedia Commons // Public Domain

Ansel Adams was a genius with a camera, but he wasn’t so great about taking notes. The famous 20th century landscape photographer did not keep careful records of the dates he took his photos, leading to some debate over the origin period of certain images, including Denali and Wonder Lake (below), taken in Denali National Park in Alaska sometime in the late 1940s.

A black-and-white photo of Denali as seen from across Wonder Lake
Denali and Wonder Lake
Collection Center for Creative Photography, The University of Arizona, © The Ansel Adams Publishing Rights Trust

To settle a debate about when the photograph (known as Mount McKinley and Wonder Lake until the mountain's name was officially changed in 2015) was taken, Texas State University astronomer Donald Olson looked to the sky, using astronomical hints to determine the exact date, time, and location it was shot. Olson—who has solved other cultural mysteries related to topics such as Edvard Munch's paintings and Chaucer's writing using the night sky—writes about the process in his new book, Further Adventures of the Celestial Sleuth.

Adams did take some technical notes during his photography shoots, writing down the exposure time, film type, filters, and other settings used to capture the image, but he wasn’t as meticulous about the more mundane parts of the shoot, like the date. However, during his research, Olson found that another photo, Moon and Denali, was taken the night before the image in question. Because that one featured the moon, he could use it to calculate the date of both images—once he figured out where Moon and Denali was taken.

The moon hangs in the sky over Denali in a black-and-white photo
Moon and Denali
Collection Center for Creative Photography, The University of Arizona, © The Ansel Adams Publishing Rights Trust

To do so, Olson used topographical features such as cirques, hollowed landforms carved by glaciers, that were visible in Moon and Denali to identify several areas of the park where Adams may have been working. He and his student, Ava Pope, wrote a computer program to calculate the view from each possible location along the park road Adams drove along during his trip, eventually determining the coordinates of the location where the photographer shot Moon and Denali.

He could then estimate, using the position of the waxing gibbous moon in the photo, the exact time —8:28 p.m. on July 14, 1948—that Moon and Denali was taken. Denali and Wonder Lake would have been taken the next morning, and Olson was able to calculate from the shadows along the mountain where the sun would have been in the sky, and thus, when the photo was taken.

The answer? Exactly 3:42 a.m. Central Alaska Standard Time on July 15, 1948.

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