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Mercury magazine

Spring 2016 - Volume 45, Number 2

Spring 2016 - Volume 45, Number 2

Table of Contents



[20] New Horizons and the Exploration of the Pluto System, Alan Stern
For all of us who worked on New Horizons, the flyby of Pluto was an unbelievable experience of scientific discovery.

[29] Mars in 2016: A Close Approach, Paul Deans
Don’t miss bright Mars, now appearing in our spring and early summer sky.

[34] Touring to Totality in 2017, Paul Deans
Even if the eclipse is in your own back yard, joining a tour to totality in 2017 has certain benefits.

[40] Astronomy in the News
Explaining the sustained eruptions on Enceladus, longest-lasting stellar eclipse discovered, and the first discovery of a binary companion for a Type Ia supernova. These are some of the discoveries that recently made news in the astronomical community.


[4] Perspectives, Paul Deans
A Fool for Planets

[5] First Word, Linda Shore
Harassment, Diversity, and Inclusion at the ASP

[6] Annals of Astronomy, Clifford J. Cunningham
Villum Lange

[7] Astronomer’s Notebook, Jennifer Birriel
Type Ia Supernovae: Progenitors and Host Galaxies

[9] Planetary Perspectives, Emily Joseph
Dawn at Ceres: An Update

[11] Strange New Worlds, Australian National University in Canberra
The Aliens Are Silent Because They Are Extinct

[12] Armchair Astrophysics, Christopher Wanjek
Catch a (Gravitational) Wave and You’re Sitting on Top of the World

[14] Education Matters, Brian Kruse
Thinking About Space

[16] Reaching Out, Bethany Cobb
Gravitational Waves Detected and Explained

[18] ASP’s Statement on Harassment and Commitment to Diversity and Inclusion

[48] ASP Tidings
ASP Awarded NASA Education Contracts

[50] Sky Sights, Paul Deans
A Transit of Mercury and Mars in Passing

[53] Reflections, ESA/Rosetta
The Origins of a Coma

New Horizons and the Exploration of the Pluto System

by Alan Stern

For all of us who got to work on New Horizons, the flyby of Pluto was an unbelievable experience of scientific discovery. And I think that for most people on the team, it was actually emotional. We worked very hard for 15 years to build that spacecraft, get it launched, get it across the solar system, and plan the flyby itself. Pluto turned out to be spectacular, and so did its satellite system.

But it wasn’t just our science team that was interested. The public turned out in droves, and I think this is a very important lesson for our entire community. People really love exploration. They love what we do in planetary science. And we worked very hard before the flyby — for four years — to try and drive public interest in Pluto, to drive interest in New Horizons, to show what exploration is all about.

In this presentation I’ll use names of surface features on Pluto. As you know, these are all informal names that our team uses. We have not submitted them to USGS or the IAU, but we need to be able to refer to surface features, so you’ll see some of those names used here.

Mars in 2016: A Close Approach

by Paul Deans

Mars is back. Well, okay, it never really went away. But for most of the past decade, it has been glowing dimly as it made its way through the heavens. If you turned a telescope toward it — even a reasonably large amateur instrument — the red planet looked small and almost featureless. But this year Mars is putting on its best show in a decade, and it’s a prelude to 2018 when Mars will be the closest (and brightest) it has been since 2003.

Touring to Totality in 2017

by Paul Deans

Join an eclipse tour in 2017? OMG, why? you’re likely thinking. I can hear that opinion being muttered from sea to shining sea in the United States. Why join a tour to see the total solar eclipse of August 21, 2017, when it’s possible to drive to the path of totality? Well, I can think of several reasons.

Perhaps the eclipse tour goes to a part of the United States you’ve never visited — a part that’s not particularly close to home — and offers to show you sights you never even knew existed. The eclipse is a good excuse to get out and see more of the US.

Perhaps the idea of being trapped in a car for several days with assorted family members (and/or supposed friends) gives you the heebie-jeebies.

Perhaps you can already feel the knot building in your stomach as you contemplate trying to find the best site with the best weather — with expectations at an all-time high that you’ll pull it off (you are the family’s astro-geek, after all).

Or perhaps you’d prefer — to adapt a line from the classic Greyhound bus commercial — to leave the driving to someone else.

Unexpected Changes of Bright Spots on Ceres Discovered

European Southern Observatory

Ceres is the largest body in the asteroid belt between Mars and Jupiter and the only such object classed as a dwarf planet. NASA’s Dawn spacecraft has been in orbit around Ceres for more than a year and has mapped its surface in great detail. One of the biggest surprises has been the discovery of very bright spots, which reflect far more light than their much darker surroundings. The most prominent of these spots lie inside the crater Occator and suggest that Ceres may be a much more active world than most of its asteroid neighbors.

New and very precise observations using the HARPS spectrograph at the ESO 3.6-metre telescope at La Silla, Chile, have now not only detected the motion of the spots due to the rotation of Ceres about its axis, but also found unexpected additional variations suggesting that the material of the spots is volatile and evaporates in sunlight.

The lead author of the new study, Paolo Molaro, at the INAF–Trieste Astronomical Observatory, takes up the story. “As soon as the Dawn spacecraft revealed the mysterious bright spots on the surface of Ceres, I immediately thought of the possible measurable effects from Earth. As Ceres rotates the spots approach the Earth and then recede again, which affects the spectrum of the reflected sunlight arriving at Earth.”

The team observed Ceres with HARPS for a little over two nights in July and August 2015. “The result was a surprise,” adds Antonino Lanza, at the INAF–Catania Astrophysical Observatory and co-author of the study. “We did find the expected changes to the spectrum from the rotation of Ceres, but with considerable other variations from night to night.”