One of my favorite jests is that Oregon astronomers spend three months of the year looking at the sky and the remaining nine reading about it — a wild exaggeration, of course, but it captures something true about cloudy winters here.
During our outreach programs, kids' inquisitiveness compels us to address astronomy in ways that require real preparation. You can't be lazy when answering a fourth-grader. Which is why we often end up learning as much as the students when we pay a visit to class. Here is a sample of real questions from local fourth-graders — along with the answers we gave.
In the early history of the solar system, a moon strayed too close to Saturn and got torn apart by Saturn's tidal forces — much stronger than the forces our Moon exerts on Earth's oceans. Those rings are what remain of that shattered moon: tiny pieces of ice, dust, and rock. The cosmic equivalent of that shiny patina of broken glass on the road after a fender-bender.
Mauna Kea on the Big Island hosts many of the world's largest telescopes. The site is ideal because it's dark (far from city lights), there's plenty of open space, and — most importantly — the summit sits above most of the atmosphere's water vapor and turbulence, which greatly improves the quality of observations. At nearly 14,000 feet, it's a world-class site.
Yes. Most stars we see are following an orbit around the center of the Milky Way Galaxy — a journey that takes our Sun about 225 million years to complete. If you track individual stars carefully over years or decades, you'll find that virtually all of them shift their position in the sky slightly. This is called a star's proper motion. The closer the star, the more readily we can detect its movement.
The name comes from Old English words meaning "polar star." It's fitting because Polaris lies almost exactly above Earth's North Pole, so the entire sky appears to rotate around it as Earth spins. That makes it the perfect fixed reference for navigation.
In 2006, the International Astronomical Union officially reclassified Pluto as a dwarf planet. It's a fascinating world — New Horizons flew past it in 2015 and revealed surprisingly complex geology including mountains of water ice and a heart-shaped nitrogen plain. Pluto's moon Charon is so large relative to Pluto (about half its diameter) that the two are sometimes called a double dwarf-planet system.
A tough question to answer precisely — but think of it this way: there are hundreds of billions of galaxies in the observable universe. Each contains at least several dozen billion stars. The comparison that there are more stars than grains of sand on all of Earth's beaches is probably correct. In our own sky on a clear dark night, the naked eye can see about 5,000–6,000 of them.
Yes! I remember the first time clearly — it was a St. Patrick's Day, and I was so excited that I dragged the whole family away from dinner to see it. Mercury is tricky because it always stays close to the Sun, so you can only spot it low in the west after sunset or low in the east before sunrise. But that elusive quality makes finding it especially satisfying.
No, I'm afraid not. My only experience with dissection was a worm in high school biology class. We haven't yet found definitive evidence of life beyond Earth, though the search continues with missions to Mars and studies of ocean worlds like Europa and Enceladus.
Because it's so far from the Sun. Pluto orbits at an average distance of about 39 times farther from the Sun than Earth. If you stood on Pluto and looked back, the Sun would appear only as an extremely bright star — barely warmer than looking at a full Moon. Surface temperatures there average around −230°C (−380°F).
The color of the Sun comes from its temperature. Cooler stars glow red; the hottest stars burn blue-white. Stars in between — like our Sun — glow yellow, orange, or white. (Interestingly, our Sun is actually closer to white; its yellow-orange appearance is partly an artifact of looking through Earth's atmosphere.)
I rather like Earth, honestly. But if I could visit another, I'd pick Jupiter. The cloud bands you can see through even a small telescope are breathtaking — up close, you could spend years enjoying every intricate, colorful detail. Each band is a weather system that makes Earth's hurricanes seem small. And I'd love to see the moons up close: volcanic Io, the strange terrain of Ganymede, the frozen oceans of Europa. My favorite thing is watching the moons cast shadows on Jupiter's disc.
That depends on the person — there really isn't one right reason. Speaking for myself, I love looking at what the sky has to offer; there are beautiful things to see and imagine. For others it's a way to better understand nature and the universe we live in. Some find it relaxing. And those not particularly drawn to the science can still find it a useful reminder of the smallness of Earth — and the importance of taking care of it.
Because we're moving with it — traveling at the same speed as a result. When you're in a car moving steadily at 60 mph, you don't feel how fast you're going. It's the same with Earth's rotation, except that it doesn't change speed like a car does. What we can feel is any change in motion — and Earth rotates very steadily.
Our best option is Mars. Temperatures, while cold, are survivable with the right equipment. It has a solid surface, manageable gravity, and weather far less violent than many other planets. That said, we'd need spacesuits or sealed habitats — the atmosphere is thin carbon dioxide. But Mars remains humanity's most realistic near-term destination.
The International Astronomical Union officially recognizes 88 constellations that together cover the entire sky. If you travel to both the northern and southern hemispheres, you can eventually see all 88.
The fundamental difference is that the Sun makes its own energy through nuclear fusion. It's a sphere of mostly hydrogen gas so massive that the gravity at its center creates enough pressure and temperature to fuse hydrogen atoms into helium — releasing enormous amounts of energy as light and heat. Planets don't have nearly enough mass for this. They shine only by reflecting the Sun's light.
You almost certainly saw a satellite. Even small ones can be surprisingly bright when sunlight hits them at the right angle. Satellites at higher orbits appear to move more slowly across the sky than those in low Earth orbit — so a very slow-moving object was likely at altitude. See our article on satellites for more on spotting and predicting them.
About 1,300 Jupiter-sized planets could fit inside the Sun by volume. In terms of mass, the Sun is about 1,000 times heavier than Jupiter. It's a useful reminder of just how enormous our star is — and yet the Sun is just an average, middle-of-the-road star compared to the giants in our galaxy.
A comet is often described as a "dirty snowball" — mostly ice with rock and dust mixed in. When it approaches the Sun, the ice vaporizes and creates the glowing tail we see. An asteroid is essentially the opposite: mostly rock and metal (usually iron), with very little ice. See our article on asteroids for more detail.
The planets began as loose clumps forming from a disc of gas and dust orbiting the young Sun, held in place by the Sun's gravity. As those clumps grew into planets, they retained the sideways momentum from their beginnings. With nothing to slow them down in the vacuum of space, they've been orbiting ever since — for about 4.6 billion years.
Mercury has almost no atmosphere to distribute or retain heat. The sunlit side — very close to the Sun — bakes at around 430°C (800°F). The dark side has no blanket of air to hold warmth, so temperatures plunge to −180°C (−290°F). It's one of the most extreme temperature swings in the solar system.
Mercury is very hot in sunlight, but it can't hold that heat — it has virtually no atmosphere. Venus, by contrast, has a thick carbon dioxide atmosphere that traps heat through the greenhouse effect. That trapped heat raises Venus's surface temperature to about 465°C (870°F) — hot enough to melt lead — consistently on both the day and night sides.
It's a reinforced concrete and steel platform that supports a rocket before liftoff. It includes piping for fuel and fluids, elevators and walkways for crew and technicians to access the rocket, and lightning protection towers. Interestingly, Apollo 12 was struck by lightning — twice — on its way to the Moon. Fortunately, all systems survived and the mission was a success.
It's mostly about location. An asteroid (or the smaller meteoroid) is a chunk of rock in space. A meteorite is a piece of rock that has entered Earth's atmosphere and survived to hit the ground — something we can actually hold. When a meteoroid is burning through the atmosphere and glowing, we call it a meteor (or "shooting star").
Some of these questions took real effort to track down a good answer for. If you have a question for us, email hvabod@groups.io and we'll do our best.