Something 3x Wider Than Jupiter Appeared Just Past Mars

In August 2026, an object in the outer part of our inner solar system suddenly grew to about 292,000 miles across. That's more than three times the diameter of Jupiter. Two days earlier, it had not been there. Not smaller, not there, as far as anyone looking through an ordinary telescope was concerned. It sits just beyond where Mars orbits, and it's not a planet, not a spacecraft, and not a new discovery. It's a comet that has been on the books for 22 years that nobody paid attention to, and that has now exploded twice in three months. And the two explosions were chemically different from each other. Because if the two blasts brought out different material, then they both opened two different rooms inside the same object, and for a few weeks we could look into both. It's called 220P Mignot, and until this year it was one of the least interesting objects with a name. Robert Mignot founded in 2004 on images from a telescope in Australia. It showed up as a smudge at 17th magnitude, which is roughly 40,000 times fainter than the faintest star you can see with your eyes. Small comma, barely a tail, nothing remarkable. It belongs to a group called the Jupiter family. These are comets whose orbits have been reshaped by passing too close to Jupiter, which captured them into short loops around the Sun. 220P takes just under five and a half years to go around, swings out to 4.7 times the Earth-Sun distance, and back in again. Its closest approach to the Sun this time was in June, at 1.55 astronomical units. Mars orbits at 1.52, so it came into just outside where Mars travels, turned, and started heading back out. For 22 years it did this quietly, and each time it came around it was faint, and each time nobody wrote anything about it. Then it stopped being quiet. At the beginning of June, an astronomer checking images from a survey telescope noticed that 220P was not where it should be on the brightness scale. It had gone from 17th magnitude to 8th. In brightness terms, that is a factor of somewhere between 7 and 8,000, depending on which measurement you take, and it happened over a matter of days. An object that had been invisible to almost every telescope on Earth was suddenly within reach of a decent pair of binoculars. Then, as expected, it started fading. Comet outbursts do that. The material expands, thins out, and the object sinks back toward whatever brightness it had before. By late July it was back down to 12th magnitude and heading for obscurity. It is worth pausing on what a factor of 7,000 means, because brightness numbers are slippery. If a lightbulb in your house did that, it would go from a nightlight you can barely see to something you cannot look at directly. On an object made of ice and dust, sitting 150 million miles away, it means an enormous amount of material left the nucleus in a very short time. On the 5th of August, it exploded a second time. This one was smaller in relative terms, a brightening of roughly 650 times rather than 7,000. But it started from a higher baseline, and it took the comet to 6th magnitude. That is the naked-eye limit under a genuinely dark sky, and an easy target in binoculars. Two outbursts on the same comet 10 weeks apart. That is rare enough that the observing community reached for the last comparable case, which was in 1973 on a comet called Tuttle-Giacobini-Cresac, which also went off twice a few months apart and has been cited ever since as the strange one. Observers measured the comet at 7 arcminutes on the 5th and 9 on the 6th. An arcminute is a sixteenth of a degree, which sounds tiny until you convert it at that distance. 9 arcminutes at 111 million miles from Earth is about 292,000 miles across. The nucleus underneath all of that is a few miles wide. Everything else is gas and dust released from it, expanding into a sphere large enough to swallow Jupiter three times over. What came out of it and what that tells us about the inside of a comet is where this goes next. Subscribe and stay with me! On the 8th of August, two astrophotographers using a 12-inch robotic telescope in Namibia produced the image that circulated fastest, and it is worth understanding what you're looking at. There is a bright inner region and around it at a distinct edge, a curved front standing out from the rest of the cloud. That front is the leading edge of the material thrown out on August 5th, expanding outward through the older material left over from the June outburst. A shell of new debris plowing through an older debris field, sharp enough to photograph from the ground. One of them described a second detail. Through a red filter, the gas comma appeared perfectly round, while in the outer regions there were two separate shells, one nested inside the other. Two shells, two events. The comet was carrying a photographic record of both of its own explosions at the same time. Now the mechanism, and it is worth saying plainly that it is not settled. A comet nucleus is not solid rock. It is a mixture of ice, dust, and frozen gases, loosely packed with a great detail of empty space in it. As it approaches the Sun, the surface warms and the ices sublimate, turning straight from solid to gas without becoming liquid, and that is what produces the ordinary comma and tail. An outburst is something else. The leading explanations all involve something happening below the surface rather than on it. One is a phased change in the ice itself. Water ice that formed in deep space is amorphous, meaning its molecules are arranged randomly, and it traps other gases inside that structure. Warm it past a certain point, and it rearranges into ordinary crystalline ice, and everything it was holding is released at once. Another is pockets of carbon dioxide or carbon monoxide, which sublimate at much lower temperatures than water. If heat reaches one of those pockets, the pressure has to go somewhere, and the only way is out through the surface. And a third is simple structural failure. A cavity collapses, or a piece of the crust gives way, and fresh material that has never been exposed to sunlight is suddenly in direct sun. There is a way to picture the difference between the normal process and an outburst. Normal sublimation is a kettle simmering, steady, continuous, driven by the heat reaching the surface. An outburst is a bottle of busy drink that has been shaken and then opened. Nothing about the outside told you it was going to happen, and the energy came from something that was already stored inside. The spacecraft Rosetta watched an outburst happen from close range at another comet, which is the best data anybody has. And even with a spacecraft sitting next to it, the picture is incomplete. On the 8th of August, astronomers at an observatory in Bulgaria measured the comet properly, with calibrated photometry, and published the numbers two days later. There is a standard quantity used to describe how much dust a comet is producing. For a typical Jupiter family comet near the Sun, it runs somewhere between 100 and 1000. The measurements for 220P came back between 12,000 and 14,500. 10 to 100 times the normal range. But the number is not the finding. The finding is what it was made of. In August, the comet was dominated by dust-reflecting sunlight. Back in June, the eruption had been characterized by an enrichment in molecular gas. Same comet, ten weeks apart, two chemically different eruptions. Which points to something specific about the inside. If the two blasts had come from the same reservoir, they should look the same. They don't. So they came from different places. And those places have different compositions. And there is a reason that matters beyond this one comet. Jupiter family comets are among the oldest unmodified material in the solar system, assembled up beyond the planets and kept cold ever since. The layers inside them are, in effect, a record of what this whole system was made of when it formed, sorted by depth. So looking into two different rooms of a comet is not just a curiosity about that comet, it is a sample of two different moments in how the system came together. That is a rare thing to get. We can't drill into a comet. What we can do is wait for one to open itself. And this one opened twice, in two different spots, while people were watching. Here's what is not known, and there is a lot of it. Nobody can say why this comet went off twice this year and not on any of its previous four passes. Nobody can predict the next one. Outbursts are recognized after they happen, by amateurs checking images, and that is still the state of the art in 2026. There's also a claim circulating that these eruptions are connected to the solar wind, and specifically to a magnetic link between the Sun and Jupiter passing through the comet's position. It is worth saying clearly that this does not appear in the professional literature on this object, and the working explanations from the people who study comets are all internal to the nucleus. Ice chemistry, trapped gas, structural collapse. That does not make the idea forbidden to think about, it makes it an idea without evidence behind it, and the difference matters, because the actual explanation is stranger and better documented than the invented one. And the honest description of the size is this. For a few days in early August, the cloud around this comet was larger than Jupiter. It's not now. By the middle of the month, the comet had shrunk to around two arc minutes, and the brightness had fallen to ninth magnitude, which puts it back out of binocular range and heading toward the 22 years of obscurity it came from. It's in the constellation of Cetus, in the pre-dawn sky about 111 million miles away. Light from it takes just under 10 minutes to reach us, which is roughly the same as light from the Sun. It's moving outward, and it will keep fading. In a few years it will be back at Ophelian, out past the asteroid belt, and in 2031 it will come round again. Whether it does it next time, nobody knows. And there is one date worth writing down. The closest this comet will come to Earth in the entire 21st century is in August 2048, at about 55 million miles. If it's still in the habit of exploding then, that is the one to watch. There's something worth noting about how this was found. Not by a space telescope, and not by any mission. An amateur checking survey images noticed a smudge was brighter than it should be, and the measurements that the professional bulletins ended up publishing were made by people in Spain and Japan with binoculars, at 4 in the morning, from their own gardens. For a few days in August, an object more than three times the width of Jupiter was hanging just past the orbit of Mars, and it was visible to anyone who knew where to look and was willing to get up. Most of them did not know. That's usually how it goes. And that is not the only time something has appeared in our sky where nothing was. There's a set of photographic plates from the 1950s, taken before any satellite existed, that show points of light which are there in one exposure and gone in the next. Around 100,000 of them. Nobody has explained what they were. We made a whole video on it. Start there.