FTV: Spring PS Update
When the March 2026 Equinox edition of The Planetary Report (Vol. 46, No. 01) landed in my mail box, the cover image of Comet 67P/Churyumov – Gerasimenko didn’t give a hint as to the major announcement that was waiting on page 4. The image was taken by the European Space Agency’s Rosetta spacecraft in 2015 and was accompanied by the teaser headline Beyond the Planets: Comets and Kuiper Belt Objects which we will get to in a bit. The big news on page 4 informed the Planetary Society faithful that long time CEO Bill Nye (yes, the Science Guy Bill Nye) had stepped back from that role in February of 2026 after a 15 year tenure. Chief Operating Officer Jennifer Vaughn has slid seamlessly into the position but Nye assured all that he wasn’t going to ride off into the sunset when there is so much important space exploration work still to be done. As for the rest of the issue, here are some of the interesting highlights:
Back in 2006, the International Astronomical Union (IAU) declared that Pluto would no longer be called a planet. It was reclassified as a dwarf planet and the decision upset a lot of us who grew up in a solar system with nine planets orbiting the Sun. Kate Howells revisited the topic and I can now say the reclassification now makes more sense to me. As she pointed out, one will find our understanding of the solar system has made it necessary to redefine ‘planets’. The process started back with the ancient Greeks. In those days of early Greek astronomy, any object that moved against the fixed background of stars was called a ‘planet’ (a name meaning ‘wanderer’). To them, the planets included Mercury, Venus, Mars, Jupiter, Saturn, the Sun, and the Moon…but not the Earth. To them, the Earth was the stationary center of the Universe and everything revolved around us. I am guessing the human tendency to make everything ‘all about us’ isn’t a new phenomenon.
When the Sun-centered Copernican model was adopted, it placed the Sun in the middle of our Solar System and the Earth as one of the known objects orbiting it. This redefined planets as bodies that orbited the Sun, including the Earth. More members were added to the Sol family beginning with the discovery of Uranus in 1781. With better telescopes to scan the heavens, smaller objects orbiting the Sun between Mars and Jupiter were found starting with Ceres in 1801. When astronomers discovered more objects in that belt like Pallas, Juno, and Vesta, they, too, were considered to be planets. As more and more of these objects came to light, the area was eventually redefined in the mid-19th century as the Asteroid Belt – an area dominated by minor planets. The next major addition to the list of major planets after Uranus was found came in 1846 when Neptune was first predicted mathematically, then finally observed.
In 1930, a photographic plate confirmed the existence of a ninth planet – Pluto. Telescope resolution was not as advanced as it is today so the size of this fuzzy dot on film led to its size being overestimated. It wasn’t until 1978 that higher resolution photographs separated the image into two parts – Pluto and its co-orbiting companion Charon. Still, people were comfortable with calling it a planet, albeit, a small planet with a moon nearly as large as Pluto itself. When astronomers began finding more and more icy objects orbiting beyond Neptune, they dubbed the area the Kuiper Belt and noted that Pluto obviously belonged to this population (just as Ceres was a member of the Asteroid Belt). With the discovery of Eris, another Kuiper Belt body similar in size to Pluto, it compelled the IAU to redefine ‘planet’ once again rather than begin adding many more Pluto-sized planets to the family tree.
The IAU decided that a planet needed to meet three qualifications. First, the object must orbit the Sun. Second, it must be massive enough for its gravity to pull it into a spherical shape. Third, its mass must be sufficient to have cleared its orbit of all other objects, making it the dominant body in that area. Pluto met the first two requirements, but not the third. With this explanation, I finally understand the logic of what the IAU did in 2006. Personally, I would have liked to see them classify all similar sized objects as ‘Plutons’ as a nod to Pluto’s long history of being called a planet, but I am also not a voting member of the IAU.
As Howells noted: “The decision sparked debate that continues today. But the IAU’s definition doesn’t limit what’s worth studying. The worlds of the Cosmos are all fascinating regardless of size.” Not to mention, we are still learning a lot about the objects we already know about while we continue to discover new members of the Sol family.
One of the Planetary Society’s prime missions is fundraising to support NASA’s programs. In 2025, PS membership surpassed their $250,000 goal. There is more good news coming out of Washington, D.C. for 2026. First, The Planetary Society has established an office in our nation’s capital headed by their Director of Government Relations, Jack Kiraly. According to the Planetary Report, this office will attend everything, “From high-profile events and important meetings to casual member get-togethers and celebrations. This new permanent presence will elevate our work in D.C.”
Congress added to the joy when they rejected the White House’s proposed cuts to NASA’s budget. Instead, lawmakers passed a $24.4 billion NASA budget with an additional $7.26 billion added for the Science Mission Directorate – figures that are only slightly below the 2025 levels. The White House proposal called for 24 percent and 47 percent reductions from the 2025 level. By rejecting these steep cuts, NASA will not be forced to cut more than a dozen missions currently in the pipeline. Again, the Society had an impact as tens of thousands of members and friends in every state sent 100,000 messages to their representatives. No doubt a similar effort will be needed as it is anticipated that there will be similar reductions [as the original 2025 budget called for] proposed in the next budget cycle.
Dr. Bruce Betts, the Chief Scientist for the Society, offered up the following Random Space Fact: “The mass of the Sun compared to the mass of Earth is about the same ratio as the mass of a large elephant compared to the mass of a small mouse.” Dr. Betts is also in charge of the quarterly Trivia contest. The Winter Solstice question was, “In kilometers or miles, how much bigger is the Earth’s equatorial radius compared to its polar radius?” The answer was, “22 kilometers or 14 miles,” meaning the Earth is not a perfect sphere (but for a body with a 4,000 mile radius, it is pretty close).
During the last decade of my teaching career, I liked to compile a string of Dr. Bruce’s video shorts to show my students. With a two page quiz in front of them as they watched, I paused after each section so they could respond and prove they were paying attention. Some of his bits were corny, but every one of them passed along useful information. One of my favorites was a character named ‘Ecurb’ dusted off by Betts from time to time. ‘Bruce’ spelled backwards, Ecurb was his evil alter ego (think of Snidely Whiplash from Bullwinkle, the Moose). You can imagine the strange looks the kids gave me the one time I made that comparison: “Bull-who?” I will let another character (Johnny Carson’s Carnac the Magnificent) answer the Solstice issue trivia before the question is revealed: “The answer is, ‘Carl Sagan’ (pause for sidekick Ed McMahon to repeat the answer and then give a hearty belly laugh)…and the question is, “In college, when Bill Nye took Introduction to Astronomy, who was his professor?” If you are of a certain age, no explanation of Carnac or McMahon will be needed.
Let’s get back to the Solstice issue’s cover story: Since the Rosetta spacecraft visited comet 67p/Churyumov-Gerisamenko in 2014, we have learned a great deal about these icy visitors from the distant reaches of the Solar System. Long before astronomers could view them with telescopes, ancient people saw comets as, “Omens, messengers (often of doom), or divine portents” according to the PR’s Jason Davis. “Today,” he continues, “we know comets not as harbingers but as ancient assemblages of ice and dust left over from the dawn of the Solar System – time capsules carrying water and organic compounds that predate Earth itself.” Rosetta orbited 76P/C-G from 2014 to 2017, thus becoming the first spacecraft to accompany a comet as it traveled around the Sun. With this unprecedented mission, Rosetta’s suite of instruments were able to monitor how sunlight transformed the surface and atmosphere of the comet up close..
Led by Kathrin Altwegg, a science team at the University of Bern learned that there were far more organic molecules present than they anticipated. One of the long standing theories of how life developed on the Earth speculates that some of the building blocks arrived with comets or asteroids. Altwegg described their discovery: “The organics in comets like 67P were mostly produced before the Solar System was born. These organics are universal, We can even observe some of them in dark molecular clouds and star-forming regions. This means whatever led to life on Earth can happen elsewhere in the Universe.” This reminds me of one of Carl Sagan’s favorite sayings: “Everything is made of star-stuff. We are made from star-stuff.” If there are alien life forms elsewhere in the Universe, apparently they will also be made from star-stuff.
Altwegg expects we will need more missions to comets to understand the big picture. The Rosetta craft studied mostly the coma – the dust and gas that surrounds the core. As sunlight warms the surface of this nucleus, gas and dust jets erupt forming the coma. The solar wind then pushes these materials out away from the Sun to form the tail. She continued saying, “We still don’t know how the ice and dust are distributed inside or how homogeneous comets really are. To answer that, we need to visit more comets.”
The goal of a European Space Agency mission called Comet Interceptor will explore that idea, just a little deeper in space. CI, scheduled to launch in 2029, would meet a comet farther from the Sun, thus allowing it to examine a pristine comet soon after it leaves the Oort Cloud (the name given to the area beyond Pluto seen as the source of many cometary bodies). Studying the surface before sunlight begins to react with these ancient ices will tell us more about the ancient materials that formed the Solar System. No comet has been targeted yet. Comet Interceptor will park itself at the Sun / Earth L2 point (the area where gravity from the two objects are in balance) and wait until a suitable candidate comet is spotted heading into the inner Solar System.
Water is another one of the building blocks of life as we know it. As with organic materials that may have hitch-hiked here from elsewhere, many scientists have speculated that there is a similar origin story for the water we have on Earth: it arrived courtesy of comets and asteroids. Rosetta found something interesting when it took a close up look at the ices on comet 67P. The deuterium-to-hydrogen ratio in 67P’s water does not match the ratio found in water on the Earth. This suggests that only some comets and asteroids carry water similar to what we find on Earth.
Being able to look at comet ice farther from Earth and the Sun with the Comet Interceptor mission may shed more light on where the Earth’s water came from.
We have studied comets long enough to discover that those that have settled into the Kui[per Belt are more short term with orbital periods of up to 200 years. Some interact with the large outer planets and get flung further out to that vast spherical domain called the Oort Cloud (named for Jan Oort, who first postulated its existence). Present theories suggest the Oort Cloud may stretch halfway to our nearest stellar neighbor, Proxima Centauri. If Proxima also has its own Oort Cloud, perhaps it interacts with our’s – maybe even to the extent that we could see comets originating from another star besides our own. More data is needed. Thus far, all of the comets we have visited (67P, Giacobini-Zinner, Grig-Skjellerup, Halley, Borrelly, Wild 2, Tempel 1, and Hartley 2) have been short term comets more than likely sourced from the Kuiper Belt.
Just to make it more interesting, cometary astronomy has also discovered some can be classified as being ‘warm’. According to Davis, “Not every comet fits neatly into ‘short’ or ‘long’ categories, Some orbit within the main asteroid belt, while others skim the Sun or fade into dormant, rocky relics. These transitional worlds blur the line between asteroids and comets, revealing how one population evolves into the other.” Yes, the more we encounter these ancient chunks of astro-real estate, the more we uncover about the secret lives of comets.
We will let Davis summarize the whole comet mystery: “Each comet we study is a messenger from the Solar System’s earliest days. They carry the raw ingredients that built planets, oceans, and perhaps life itself, preserved in ice and dust for billions of years. By examining these icy travelers, we glimpse the processes that shaped Earth and the worlds around us. We can’t return to those first moments, but through comets, we can hear the whispers of our cosmic origins.”
Finally, let me add a hearty ‘well done and best wishes’ to Bill Nye as he passes the leadership torch. We are fully confident that he will be just as busy behind the scenes promoting space exploration as he has been leading the charge.
Top Piece Video: From Live at Pompeii – What says ‘voluntary contributions to space exploration’ like Pink Floyd’s Set the Controls for the Heart of the Sun? Okay, a bit of a stretch, but a good excuse to revisit Pompeii!