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Mercury magazine

Autumn 2017 - Volume 46, Number 4

Autumn 2017 - Volume 46, Number 4

Table of Contents



[18] Eclipse Chronicles, Various Authors
Seven tales from the Great American Solar Eclipse of 2017.

[29] A Nation of the Stars, Steve Murray
Observatories in Chile give back to the people who give them dark skies.

[34] Extrasolar Planets: The Saga Continues, Paul Deans
We’re finding plenty of exoplanets, but are any of them suitable for life as we know it?

[40] Astronomy in the News
New Horizons’ next target just got more interesting, scientists recover a nova first spotted 600 years ago, and gravitational waves from a pair of colliding neutron stars have been detected.


[4] Perspectives, Paul Deans
Thanks, and Farewell

[5] First Word, Linda Shore
A Solar Eclipse in a Western Town

[7] Annals of Astronomy, Clifford Cunningham
How Far Away Are the Planets?

[8] Astronomer’s Notebook, Jennifer Birriel
Habitability: Are Two Suns Better than One?

[10] Strange New Worlds, Elizabeth Landau
TRAPPIST-1 is Older Than Our Solar System

[11] Planetary Perspectives, Emily Joseph
Cassini End of Mission: A Personal Perspective

[12] Armchair Astrophysics, Christopher Wanjek
Old Bursts Still Teaching Us New Tricks

[14] Education Matters, Brian Kruse
Sharing the Phenomena

[16] Reaching Out, Bethany Cobb
Partial Eclipse, Total Outreach

[48] ASP Tidings
ASP Award Recipients; a new book for the ASP’s AstroShop

[54] Sky Sights, Paul Deans
Meteor showers and a lunar eclipse

[57] Reflections, NASA/Mindaugas Macijauskas
A View Not Soon Seen Again

Eclipse Chronicles

by Various Authors

The experience of witnessing a total solar eclipse is one that inspires awe, amazement, wonder, and elation in just about every person who sees one. Just ask someone who traveled to “the line” and they will probably tell you that they were unprepared for the emotional power of the event. The day after the eclipse, I spent hours sharing the excitement with dozens of people who wanted to share their experiences with me (in equal parts eclipse euphoria and traffic horror). Even though their feelings were deeply personal and moving, the desire of many people is to share those feelings with others.

Having seen the eclipse in Hawaii in 1991, I was anxious to share the experience with my family and friends this time. I had been talking about it with my children for several years and they were excited to go. In the months leading up to August 21st, I worked to get as many people as possible to the county fairgrounds in Riverton, Wyoming — a location near the centerline chosen for its large parking lot and clean public rest rooms. Logistics trumped landscape, in this case, but we were thrilled to have a large open area near the rodeo grounds where we could set up telescopes and share the eclipse.

A Nation of the Stars

by Steve Murray

Finding the oldest galaxies. Identifying the source of gamma ray bursts. Measuring the expansion rate of the universe. These and other major discoveries have come from telescopes high in the deserts of Chile. International astronomy has flourished here for almost 60 years, thanks to the country’s dry air and dark skies, and Chile promises to dominate the future of astronomy, as well. At current rates of construction, the nation will host 75 percent of the world’s astronomical observing capacity by 2025.

While amazing scientific work is taking place at the observatories, quieter work is occurring around them. Education and outreach specialists with the organizations that manage these sites are engaged with Chilean universities, schools, and local communities to make sure that everyone in the country benefits from their presence. Chileans think of themselves as a nation of the stars. It’s the job of these specialists to foster that tradition.

Extrasolar Planets: The Saga Continues

by Paul Deans

You remember TRAPPIST-1. The detection of seven planets orbiting an ultra-cool red dwarf star generated multiple headlines in February 2017. In case you missed it, here’s a NASA press release about the discovery. The Spring 2017 issue of Mercury (page 17) featured an article with a more general discussion of planets orbiting red dwarf stars.

Then there’s Proxima Centauri b, a discovery announced in August 2016. At slightly more than four light-years distance, Proxima is the closest star to Earth (other than our Sun). Proxima b orbits its cool, red, parent star every 11 days and has a temperature suitable for liquid water to exist on its surface.

Now, some astronomers have begun searching for a planet (or planets) around Barnard’s Star, a low-mass red dwarf some six light-years away. Its main claim to fame is its rapid proper motion across the sky (a function of its close proximity to Earth). Oh, and during the 1960s, the Dutch astronomer Piet (Peter) van de Kamp claimed that there were one or more planets orbiting the star, a claim refuted in the mid-1970s.

What’s common to all three stories? Red dwarfs.

New Horizons’ Next Target Just Got a Lot More Interesting


Could the next flyby target for NASA’s New Horizons spacecraft actually be two targets? New Horizons scientists look to answer that question as they sort through new data gathered on the distant Kuiper Belt object (KBO) 2014 MU69, which the spacecraft will fly past on January 1, 2019.

The ancient KBO, which is more than four billion miles from Earth, passed in front of a star on July 17, 2017. A handful of telescopes deployed by the New Horizons team in a remote part of Patagonia, Argentina were in the right place at the right time to catch its fleeting shadow — an event known as an occultation — and were able to capture important data to help mission flyby planners better determine the spacecraft trajectory and understand the size, shape, orbit, and environment around MU69.

Based on these new occultation observations, team members say MU69 may not be not a lone spherical object, but suspect it could be an “extreme prolate spheroid” (think of a skinny football) or even a binary pair. The odd shape has scientists thinking two bodies may be orbiting very close together or even touching — what’s known as a close or contact binary — or perhaps they’re observing a single body with a large chunk taken out of it.

The size of MU69 or its components also can be determined from these data. It appears to be no more than 20 miles long, or, if a binary, each component is about 9-12 miles in diameter.