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Mercury Magazine Spring 2017

Mercury Spring 2017 coverContents and Select Excerpts
Vol. 46 No. 2
Spring 2017

If you think corona is a beer and first contact is a sports term, and you’re planning to watch August’s solar eclipse, “Coming to Terms with Solar Eclipses” will help you recognize and understand eclipse terminology. “Solar Eclipse Eye Safety: Facts and Fallacies” is an excellent summary of when it’s safe (and not safe) to look directly at the Sun during the eclipse. Both articles are in the latest issue of Mercury.

This page contains the table of contents and select excerpts only and is not a complete reproduction of this issue. Complete content for online Mercury is available to ASP members and institutional subscribers. Already a member? You can retrieve the latest issue of Mercury by logging into the ASP membership portal.


Table of Contents

[17] Earth-Sized Planets: The Newest, Weirdest Generation, Pat Brennan
Small, rocky worlds orbiting red dwarfs will be primary targets in the search for life beyond the solar system.

[22] Coming to “Terms” with Solar Eclipses, Paul Deans
Everybody talks in jargon. Here are some important eclipse terms and what they mean, so you can understand your fellow eclipse chasers this August.

[28] Solar Eclipse Eye Safety: Facts and Fallacies, Richard Tresch Fienberg
It is perfectly safe to look at the totally eclipsed Sun, but caution is needed at all other times.

[33] Astronomy in the News
Saturn’s tiny moon Pan is revealed, a tail of two pulsars’ tails, and dark matter may have been less influential in galaxies in the early universe. These are some of the discoveries that recently made news in the astronomical community.


Departments

[4] Perspectives, Paul Deans
History on the Move

[5] First Word, Linda Shore
Contemplating the Value of Exoplanets and Fruit Flies

[7] Annals of Astronomy, Clifford Cunningham
Alternative Facts

[8] Astronomer’s Notebook, Jennifer Birriel
The Making of “Messy” Planetary Nebulae

[10] Strange New Worlds, Max Planck Institute for Astronomy
Atmosphere Around Low-Mass Super-Earth Detected

[11] Planetary Perspectives, European Space Agency
A Warm Time at the South Pole

[12] Armchair Astrophysics, Christopher Wanjek
Answer to Galaxy Formation Is Blowing in the Black Hole Wind

[14] Education Matters, Brian Kruse
Earth and Exoplanets, Evolution and Climate Change

[15] Reaching Out, Bethany Cobb
Drawing Bad Conclusions from Minimal Data

[42] ASP Tidings
Help Create the Eclipse Megamovie

[44] Sky Sights, Paul Deans
A Great Time to Observe Jupiter

[47] Reflections, NASA/JPL
Splat!


Earth-Sized Planets: The Newest, Weirdest Generation

by Pat Brennan

One of the unusual features of the TRAPPIST-1 planets is how close they are to each other — so close that details on nearby planets could be easily visible from the surface of each one.

One of the unusual features of the TRAPPIST-1 planets is how close they are to each other — so close that details on nearby planets could be easily visible from the surface of each one. Courtesy NASA/JPL-Caltech/T. Pyle (IPAC)

A bumper crop of Earth-size planets huddled around a red dwarf star could be little more than chunks of rock blasted by radiation, or cloud-covered worlds as broiling hot as Venus. Or they could harbor exotic lifeforms, thriving under skies of ruddy twilight.

Scientists are pondering the possibilities after February’s announcement of the discovery of seven worlds orbiting a small, cool star some 40 light-years away, all of them in the ballpark of our home planet in terms of their heft (mass) and size (diameter). Three of the planets reside in the “habitable zone” around their star, TRAPPIST-1, where calculations suggest that conditions might be right for liquid water to exist on their surfaces — though follow-up observations are needed to be sure. All seven are early ambassadors of a new generation of planet-hunting targets.

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Coming to “Terms” with Solar Eclipses

by Paul Deans

Totality as seen from Easter Island on July 11, 2010. This is a composite of short, medium, and long exposures, as no single exposure can capture the huge range of brightness exhibited by the solar corona. No filter was used during the exposures, as totality is about as bright as the full Moon and just as safe to look at.

Totality as seen from Easter Island on July 11, 2010. This is a composite of short, medium, and long exposures, as no single exposure can capture the huge range of brightness exhibited by the solar corona. No filter was used during the exposures, as totality is about as bright as the full Moon and just as safe to look at. Courtesy Dennis di Cicco/Sky & Telescope.

When I attend an astronomy conference (of amateurs or professionals), I understand most of the terms, jargon,
and acronyms being bandied about. But if I go to, say, a gathering devoted to biodiversity, I’m lost. I need a translator to understand the terminology everyone is casually tossing around.

So if you’ve never seen a total (or even a partial) eclipse of the Sun, and you’re getting ready for the upcoming eclipse by trying to read and understand articles about eclipses in general and August 2017 in particular, you, too, may need a translator. Umbraphiles, solar-eclipse aficionados who will do almost anything to see totality, speak their own language. And whether you’re thinking of going to this year’s eclipse by yourself, with family and friends, or as part of a group, you are bound to run into people uttering eclipse jargon.

Here are some words and phrases that describe various aspects of solar eclipses. Most relate to the partial phases and a total eclipse of the Sun, but some are specific to another type of solar eclipse — an annular.

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Solar Eclipse Eye Safety: Facts and Fallacies

by Richard Tresch Fienberg

The total solar eclipse of November 14, 2012, as seen from aboard the cruise ship Paul Gauguin in the South Pacific. This sequence runs from lower right to upper left. During the partial phases, the camera lens was covered by a safe solar filter. No filter was used during totality.

The total solar eclipse of November 14, 2012, as seen from aboard the cruise ship Paul Gauguin in the South Pacific. This sequence runs from lower right to upper left. During the partial phases, the camera lens was covered by a safe solar filter. No filter was used during totality. Courtesy Rick Fienberg/TravelQuest International/Wilderness Travel.

When it comes to solar eclipses, eye safety is one of the areas that people are extremely confused about. You might suffer a little cognitive dissonance on this, because every telescope you’ve ever seen probably has a little sticker on it that says: “Don’t use this telescope to look at the Sun.” Similarly, your mother probably told you never to look at the Sun…ever!

But you also see lots of pictures of the Sun, and you hear about many solar observations by amateur astronomers. All experienced astronomers know that you just have to have the right equipment. With a proper filter over the front of your telescope, and a cap over your finderscope or any other optics, you can safely look at the Sun.

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Evidence for a Habitable Region Within Enceladus

Southwest Research Institute

During Cassini’s deepest dive through the Enceladus plume, SwRI scientists discovered hydrogen gas in the material erupting from the Saturnian moon. This discovery provides further evidence for hydrothermal activity (illustrated here) and heightens the possibility that the ocean of Enceladus could have conditions suitable for microbial life.

During Cassini’s deepest dive through the Enceladus plume, SwRI scientists discovered hydrogen gas in the material erupting from the Saturnian moon. This discovery provides further evidence for hydrothermal activity (illustrated here) and heightens the possibility that the ocean of Enceladus could have conditions suitable for microbial life. (NASA/JPL-Caltech)

Scientists from Southwest Research Institute (SwRI) have discovered hydrogen gas in the plume of material erupting from Saturn’s moon Enceladus. Analysis of data from NASA’s Cassini spacecraft indicates that the hydrogen is best explained by chemical reactions between the moon’s rocky core and warm water from its subsurface ocean. The SwRI-led team’s discovery suggests that Enceladus’ ocean floor could include features analogous to hydrothermal vents on Earth, which are known to support life on the seafloor.

“Hydrogen is a source of chemical energy for microbes that live in the Earth’s oceans near hydrothermal vents,” said SwRI’s Dr. Hunter Waite, principal investigator of Cassini’s Ion Neutral Mass Spectrometer (INMS). “Our results indicate the same chemical energy source is present in the ocean of Enceladus. We have not found evidence of the presence of microbial life in the ocean of Enceladus, but the discovery of hydrogen gas and the evidence for ongoing hydrothermal activity offer a tantalizing suggestion that habitable conditions could exist beneath the moon’s icy crust.”

On the Earth’s ocean floor, hydrothermal vents emit hot, mineral-laden fluid, allowing unique ecosystems teeming with unusual creatures to thrive. Microbes that convert mineral-laden fluid into metabolic energy make these ecosystems possible.

“The amount of molecular hydrogen we detected is high enough to support microbes similar to those that live near hydrothermal vents on Earth,” said SwRI’s Dr. Christopher Glein, a pioneer of extraterrestrial chemical oceanography. “If similar organisms are present in Enceladus, they could ‘burn’ the hydrogen to obtain energy for chemosynthesis, which could conceivably serve as a foundation for a larger ecosystem.”

“Everything indicates that the hydrogen originates in the moon’s rocky core,” Waite said.

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