Scientists Celebrate Pluto’s Discovery With A Retrospective Of Its Greatest Images
“In 1978, our telescopes had advanced enough to determine that it had a large satellite: the giant moon Charon. Through occultations of distant stars, we determined Pluto had an atmosphere that changed over time, growing larger near perihelion. 1994 saw the first optically-corrected pictures of the Pluto-Charon system by Hubble, the first image to resolve these worlds independently.”
On this date in 1930, the first world beyond Neptune in our Solar System was discovered. Now known as Pluto, our images and understanding of it have progressed dramatically through the years. It is one of nature’s most fascinating objects, and our ever-improving sights of the world are only eclipsed by the scientific knowledge we’ve continued to glean. It’s the largest object in all the Kuiper belt with five moons of its own, and it tells a story unique in all the Universe.
Come celebrate Pluto’s discovery with a retrospective of its greatest images, and our greatest science hits (so far) today!
Ask Ethan: Why don’t comets orbit the same way planets do?
“Why [do] comets orbit the Sun in a parabolic path, unlike planets which orbit in an elliptical one? Where do comets get the energy to travel such a long distance, from the Oort cloud to the Sun & back? Also, how could interstellar comets/asteroids come out of their parent star [system] and visit other ones?”
When we see comets in our Solar System, they can be either periodic, passing near the Sun and then extending very far away, to return many years later, or they could be a one-shot deal. But comets are driven by the same gravitational laws that drive the planets, which simply make fast-moving, nearly-circular ellipses around the Sun. So what makes these orbits so different, particularly if they’re obeying the same laws? Believe it or not, most of the would-be comets out there are moving in exactly the same nearly-circular paths, only they’re far more tenuously held by the Sun. Gravitational interactions might make small changes in their orbits, but if you’re already moving very slowly, a small change can have a very big effect!
Why don’t comets orbit the same way as the planets? Find out on this edition of Ask Ethan!
Are Mass Extinctions Periodic, And Are We Due For One?
“If we start looking at the craters we find on Earth and the geological composition of the sedimentary rock, however, the idea falls apart completely. Of all the impacts that occur on Earth, less than one quarter of them come from objects originating from the Oort cloud. Even worse, of the boundaries between geological timescales (Triassic/Jurassic, Jurassic/Cretaceous, or the Cretaceous/Paleogene boundary), and the geological records that correspond to extinction events, only the event from 65 million years ago shows the characteristic ash-and-dust layer that we associate with a major impact.”
65 million years ago, a catastrophic impact from outer space caused the last great mass extinction on Earth, destroying 30% of the species that lived on our world at the time. These mass extinction events happened many times in Earth’s past, and the Solar System also passes through denser stellar regions of space periodically, as determined by the orbit of the Sun and stars in the Milky Way. It’s a combination of facts that might make you wonder whether the extinction events are also periodic, and if so, whether periodic impacts are predictable. If so, then shouldn’t we be aware of whether we’re living in a time of increased risk, and prepare ourselves for that possibility accordingly? After all, the dinosaurs didn’t have a space program or the capability of deflecting a dangerous object like the one that wiped them out.
But before we go that route, we should take a good look at what the data shows. Are mass extinctions periodic? Are we due? Let’s find out!
The Scientific Truth About Planet Nine, So Far
“The most surprising results from the Kepler mission was that the overwhelming majority of planets in the Universe were not small, rocky worlds like Earth or Mars, nor large, gas giant worlds like Neptune or Jupiter, but rather in-between worlds, collectively classified as Super-Earths. Ever since that discovery, astronomers have wondered why there simply aren’t any of those worlds in our Solar System. If the Planet Nine hypothesis is right, then there actually is one, and this is the best season for finding it!”
In January of last year, astronomers Konstantin Batygin and Mike Brown shocked the world by proposing that there was a world larger than Earth located some five-to-ten times as distant as Neptune. That this world — known as Planet Nine — was causing the ultra-distant Kuiper belt objects we’d discovered so far to all have predicable, peculiar properties. And the observations matched up really well. But in science, post-dictions aren’t enough. You need to make new predictions for objects you can then go out and measure, and see how they line up. In the case of Planet Nine, there are four pieces of indirect evidence that can be measured, and one piece of direct evidence that will settle the issue once and for all: actually locating Planet Nine.
The indirect evidence looks good, and we’re fast approaching the best season for hunting Planet Nine. Come get the status update today!