Author Archives: Mark Showalter

About Mark Showalter

Planetary astronomer Mark Showalter studies the dynamics of rings and small moons in the Solar System. Known for his persistence in planetary image analysis, Mark's early work with Voyager data led to the discoveries of Jupiter's faint, outer "gossamer" rings and Saturn's tiny ring-moon, Pan. His work with the Hubble Space Telescope starting in 2003 has led to the discoveries of "Mab" and "Cupid," small moons of Uranus now named after characters from Shakespeare's plays. His work also revealed two faint outer rings of dust encircling the planet. In 2011, Mark initiated a Hubble observing program focused on Pluto, which has led to the discoveries of two tiny moons. Their names, "Kerberos" and "Styx", were selected through an international naming campaign. Most recently, Mark discovered the 14 known moon of Neptune, which is designated "S/2004 N 1" until its permanent name can be selected. He is a co-investigator on NASA's Cassini mission to Saturn and its New Horizons mission to Pluto.

The Three Discoveries of Pan

This morning, NASA's Cassini spacecraft obtained the first closeup images of Saturn's innermost moon, Pan. The images show a peculiar body shaped like a "flying saucer". Pan occupies a unique position in the rings, at the center of the 300-km ...

Our Predictions about Pluto: Getting it Right/Getting it Wrong

Back in June, my research colleage Doug Hamilton and I put out a paper in Nature magazine about the four small moons of Pluto. The timing was not accidental. Although the paper was the culmination of years of work with ...

The Slumbering Dwarf Awakens: Pluto is about to come back into the limelight

After the busiest July of our lives, the New Horizons team members have finally caught up on sleep. A few of us have even had a chance to take vacations. It's good that we're rested up, because an onslaught of ...

Telling Pluto’s Story, One Fragment at a Time

When you begin a new research project, you usually have expectations about where it will lead. Most projects take you or less to the expected destination. Some go nowhere. However, every now and then a project picks you up and ...

New Explorers on the OurPluto Ballot, April 2

We have added three new historic explorers to the OurPluto ballot today. Keep those great ideas coming in! I have been learning so much. Several people nominated the renowned 10th-century explorer and cartographer Muhammad al-Idrisi. He traveled as far west as ...

More Nominations for OurPluto

We continue to receive a fascinating collection of nominees for the OurPluto campaign. Here are a few that we recently added to the ballot. Several wrote to remind us of the iconic prints by Gustav Doré, a French artist from the ...

OurPluto Campaign, Day 6

The OurPluto naming campaign has been an exhilarating experience for me so far. The amount of thought that our site visitors have been putting into their nominations astounds me. You can visit the Site News page for regular updates. Today I ...

Pluto and Charon, before and after

The Mapping of Pluto Begins Today

Pluto is just 3.5 pixels across in the latest images from the New Horizons spacecraft. That's nine square pixels. You can't do much with nine pixels. You might be able to see crude patterns of light and dark, but you ...

Thanks, Anna!

How to Photograph a Racehorse …and how this relates to a tiny moon of Neptune

The name Eadweard James Muybridge does not roll off the tongue, but we have all seen his images. In the earliest days of photography, he pioneered the use of the newly-invented camera to study animals and people in motion. In ...