It’s time to redefine what qualifies as a planet

PLANET OR NOT? A group of planetary scientists label Pluto and many other orbs in the solar system as planets, despite the definition set down by the International Astronomical Union in 2006.

Pluto is a planet. It always has been, and it always will be, says Will Grundy of Lowell Observatory in Flagstaff, Arizona. Now he just has to convince the world of that.

For centuries, the word planet meant “wanderer” and included the sun, the moon, Mercury, Venus, Mars, Jupiter and Saturn. Eventually the moon and sun were dropped from the definition, but Pluto was included, after its discovery in 1930. That idea of a planet as a rocky or gaseous body that orbited the sun stuck, all the way up until 2006.

Then, the International Astronomical Union narrowed the definition, describing a planet as any round object that orbits the sun and has moved any pesky neighbors out of its way, either by consuming them or flinging them off into space. Pluto failed to meet the last criterion (SN: 9/2/06, p. 149), so it was demoted to a dwarf planet.

Almost overnight, the solar system was down to eight planets. “The public took notice,” Grundy says. It latched onto the IAU’s definition — perhaps a bit prematurely. The definition has flaws, he and other planetary scientists argue. First, it discounts the thousands of…

The Planetary Society Has a Few Tips for the President

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As the CEO of The Planetary Society, Bill Nye has written an open letter to President Trump, highlighting the need for prioritizing space research, and for supporting NASA’s space exploration efforts in particular. Bill Nye offers the president a comprehensive five-point plan for steering NASA’s objectives and orientation during his tenure:

1. Keep Mars as the Goal
Mars became the central objective of NASA’s efforts during the previous administration, and Bill Nye urges a continued focus on the same path. It is also important to insist on Mars because there are voices in the Trump administration that want to divert resources away from the Red Planet and focus on exploration of the moon. A vocal example of this is Newt Gingrich who has advocated “a permanent moon base”. For Bill Nye and The Planetary Society, a diversion of efforts to the moon would mean that a manned mission to Mars might be delayed by a generation.

2. Orbit Mars First
This point has emerged from earlier work at The Planetary Society, such as workshops on solving problems of inhabiting Mars, which have found that orbital engagement should precede a full landing on the Red Planet. This was the original strategy for the moon landing, where Apollo VIII orbited the moon and Apollo XI landed on it. The Planetary Society has suggested that in an orbital-first strategy, humans can be stationed in Mars’ orbit by 2033, and thereafter landed on the Mars surface by 2039.

3. Expand NASA’s Scientific Programs
Bill Nye draws attention to the ‘jobs’ element of NASA’s contribution, pointing out that there are tens of thousands of high-skilled jobs in engineering, manufacturing, and the pure sciences, that exist specifically thanks to NASA’s scientific programs. The report recommends that “at least 30 percent of NASA’s total budget be committed to its Science Mission Directorate,” and that we don’t forget two things: our curiosity and safety. A budget commitment to the science mission “will help humanity better understand its origins, protect us from solar storms, search for life beyond Earth, as well as understand our changing climate,” says the report. NASA’s acting administrator, Robert Lightfoot, has already stated that because of Trump’s proposed budget, the agency “will not pursue the Asteroid Redirect Mission (ARM).” Here’s why that matters. Trump signed the ‘NASA Transition Authorization Act of 2017’ on March 21, which seems to favor stability over progress, leaving…

In new Cassini portraits, Saturn’s moon Pan looks like pasta

Pan in Cassini image
This week, Cassini captured the closest images ever taken of Pan, a small moon that orbits amid Saturn’s rings.

Saturn serves up the closest thing to space pasta, the latest round of images from NASA’s Cassini probe, released March 9, show.

On March 7, the spacecraft snapped a series of portraits of Pan, Saturn’s small moon that orbits within a 325-kilometer gap in one of the planet’s rings. Taken at a distance of 24,572 kilometers from the moon, these are the closest images of Pan to date.

The close-ups could help refine astronomers’ understanding of the mini moon’s geology and…