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Emily LakdawallaMarch 12, 2019

The March Equinox Issue of The Planetary Report Is Out!

Inside the Ice Giants

I’m very pleased to announce the publication of the March Equinox issue of The Planetary Report: “Inside the Ice Giants.” The print issue shipped to members yesterday!

Inside the Ice Giants

I’ve been intrigued by the blue planets Uranus and Neptune since childhood, and I knew as soon as I took on the role of editor that I’d want to give these planets the respect they deserve with a feature article about what’s changed at Uranus and Neptune since the Voyager flybys and how we might explore them in the future. Amy Simon, who leads the Hubble Space Telescope effort that photographs these beautiful worlds at every opposition, wrote that feature for you.

To accompany Simon’s article, I asked image processing artist Björn Jónsson to take another look at the Voyager 2 images of Uranus and Neptune and compare them directly in size and color. Here’s what he came up with:

Uranus and Neptune

NASA / JPL-Caltech / Björn Jónsson

Uranus and Neptune
Only Voyager 2 has visited the ice giants, Uranus (left) in 1986 and Neptune (right) in 1989. These Voyager portraits are newly reprocessed to show the 2 planets at correct relative size and color. Since Voyager, planetary astronomers have studied the ice giants from Earth and have seen their faces change.

One of the reasons that planetary scientists want to explore our solar system’s ice giants is that mini-Neptune-sized worlds are the most common ones discovered by the Kepler mission, yet we know little about them. In her feature article, Hannah Wakeford of the Space Telescope Science Institute presents what we have managed to learn about what these super-Earths or mini-Neptunes are made of. We get a quick tour of some of the fascinating diversity of extrasolar planets.

A Comparison of Mass and Radius for Discovered Planets

Emily Lakdawalla and Loren A. Roberts for The Planetary Society based on data from exoplanets.org

A Comparison of Mass and Radius for Discovered Planets
This graph displays all exoplanets with measured diameters and masses. Rocky planets form a tight line (lower left), but super-Earths/mini-Neptunes have widely varying atmospheres and densities. At Jupiter’s size, increasing mass no longer increases the diameter of a planet (upper right). Most of Kepler’s discoveries would be in the super-Earth/mini-Neptune region, but few of them have measured masses, so they do not appear here. This graph was originally published in "The Skies of Mini-Neptunes," an article by Hannah Wakeford for the March 2019 issue of The Planetary Report.

Accompanying Wakeford’s article is a still version of Ethan Kruse’s delightful Kepler Orrery, the animated version of which you can see here.

In this issue’s pages you’ll also get updates on Planetary Society projects from Deep Drill to LightSail to our advocacy efforts in Washington. You’ll also learn about a crucial planning effort that has been a long time coming. In “Your Place in Space,” Bill Nye presents you The Planetary Society’s strategic framework [link], which clarifies our mission, our vision, and the scope of our activities. I’m excited to do the work to fulfill those plans through the coming five years.

The Planetary Report is free and open-access. It is made possible through the generous support of our members. If you’d like to support our work to bring the wonders of other worlds to the public, I encourage you to join or donate.

Read more: The Planetary Report

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Headshot of Emily Lakdawalla (2017, alternate)
Emily Lakdawalla

Senior Editor and Planetary Evangelist for The Planetary Society
Read more articles by Emily Lakdawalla

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