Explore the universe through accessible explanations of stars, planets, galaxies, and the forces that shape space. Discover how celestial objects form, why astronomical events happen, and what scientists have learned about the cosmos. This category connects everyday questions about the night sky with the bigger picture of our universe.
Astronomy & Space How eclipses can happen even though the Sun is vastly larger than the Moon
IntroductionEclipses can seem mysterious: how can the much smaller Moon hide the vast, blazing Sun? The short answer is ...
Astronomy & Space How astronomers can trace meteorites back to their origins
IntroductionMeteorites — rocks that survive passage through Earth’s atmosphere and land on our planet — carry chemical a...
Astronomy & Space Why the Moon is slowly moving away from Earth
IntroductionThe Moon is not fixed in place. Measurements show it is slowly drifting away from Earth — a few centimeters ...
Astronomy & Space How comets grow spectacular tails as they approach the Sun
IntroductionComets grow spectacular tails as they approach the Sun because the Sun's heat and radiation cause volatile m...
Astronomy & Space How volcanoes can erupt on worlds far colder than Earth
IntroductionVolcanoes are not just a feature of hot, Earth-like worlds. In our Solar System and beyond, volcanic activit...
Astronomy & Space The strange ways moons can influence their planets
IntroductionMoons are more than pretty points of light in a planet's sky. They can shape a planet's rotation, tilt, clim...
Astronomy & Space How the Moon can turn red during a lunar eclipse
IntroductionThe Moon sometimes appears red during a total lunar eclipse. This happens when Earth passes directly between...
Astronomy & Space Why a comet can have more than one tail
IntroductionComets often develop more than one tail when they pass near the Sun. These tails form because different mate...
Astronomy & Space The icy moon that may hide an ocean beneath its surface
IntroductionAmong the many icy worlds in our solar system, one moon stands out because scientists believe it may hide a ...
Astronomy & Space Why looking farther into space also means looking further into the past
IntroductionWhen astronomers say that looking farther into space is like looking back in time, they mean that light take...
Astronomy & Space What actually happens when a star runs out of fuel?
IntroductionStars shine because they turn mass into energy through nuclear fusion. When a star "runs out of fuel," that ...
Astronomy & Space How a planet can have seasons without being much like Earth
IntroductionSeasons are changes in climate and daylight that repeat over a planet's year. Earth’s seasons are familiar: ...
Astronomy & Space Why does space look black even when it is filled with stars?
IntroductionWhen you look up at the night sky, stars appear as bright points on a deep black background. That blackness ...
Astronomy & Space How gravity quietly shapes almost everything in the universe
IntroductionGravity is the invisible force that holds the universe together. From the fall of an apple to the motion of ...
Astronomy & Space Why Jupiter has stayed stormy for centuries
IntroductionJupiter has remained stormy for centuries because of powerful, persistent atmospheric dynamics: a huge inter...
Astronomy & Space What makes a planet wander backward across the night sky?
IntroductionWhen observers say a planet is "wandering backward" across the night sky, they are describing a familiar and...
Astronomy & Space The remarkable coincidence behind the perfect-looking solar eclipse
IntroductionThe Moon can appear to cover the Sun perfectly during some solar eclipses, producing a dramatic ring or tota...
Astronomy & Space Why some moons are more geologically active than planets
IntroductionSome moons show surprising geologic activity—volcanoes, geysers, resurfacing ice—while many planets appear q...
Astronomy & Space What makes Pluto and other dwarf planets different from major planets?
IntroductionPluto and other dwarf planets differ from the eight major planets in a few clear, scientific ways. These dif...
Astronomy & Space Why the far side of the Moon is not always dark
IntroductionThe phrase "far side of the Moon" often suggests a permanently dark, hidden place. In fact, the far side rec...
Astronomy & Space The strange world where a day lasts longer than a year
IntroductionImagine a planet where a single rotation—the length of one day—takes longer than it takes the planet to comp...
Astronomy & Space The surprising reason Mercury is not the hottest planet
IntroductionMost people assume Mercury, the planet closest to the Sun, would be the hottest in the solar system. The sur...
Astronomy & Space How Neptune was discovered before anyone clearly saw it
IntroductionThe story of Neptune’s discovery is unusual: astronomers predicted the existence and position of a planet by...
Astronomy & Space How far away can the human eye see into space?
IntroductionThe question "How far away can the human eye see into space?" invites a mix of astronomy, optics, and practi...
Astronomy & Space Why astronauts float even though gravity still exists in orbit
IntroductionAstronauts appear to float inside spacecraft, yet gravity still acts on them. This seemingly strange situati...
Astronomy & Space How Earth would look from different planets in the solar system
IntroductionHow would Earth look from different planets in the solar system? This article takes a tour through the inner...
Astronomy & Space Why the same eclipse looks different from different places
IntroductionAn eclipse is a dramatic alignment of the Sun, Moon, and Earth, but it does not look the same everywhere. Di...
Astronomy & Space How astronomers know what distant stars are made of
IntroductionAstronomers can tell what distant stars are made of without visiting them. They do this by studying the ligh...
Astronomy & Space The strange reason astronauts can watch the Sun rise again and again
IntroductionAstronauts aboard spacecraft and space stations often describe seeing the Sun rise and set many times each d...
Astronomy & Space Why total solar eclipses are possible at all
IntroductionA total solar eclipse happens when the Moon passes directly between the Sun and Earth, briefly blocking the ...
Astronomy & Space The hidden worlds orbiting far beyond Neptune
IntroductionFar beyond Neptune lies a vast, dim region of the Solar System where icy bodies, faint dwarf planets, and dy...
Astronomy & Space What would standing on an asteroid actually feel like?
IntroductionStanding on an asteroid sounds like science fiction, but it’s a useful thought experiment to explore gravity...
Astronomy & Space What would happen to Earth if the Moon disappeared?
IntroductionThe Moon is Earth's closest celestial neighbor and has influenced our planet for billions of years. If the M...
Astronomy & Space Why Uranus appears to roll around the Sun
IntroductionUranus looks like it is rolling around the Sun because its rotation axis is tilted by about 98 degrees—nearl...
Astronomy & Space What the night sky would look like from the Moon
IntroductionWhat would the night sky look like from the Moon? Peering up from the lunar surface offers a strikingly diff...
Astronomy & Space How Jupiter’s moons became worlds worth studying on their own
IntroductionJupiter’s moons were once seen as small points of light orbiting a distant planet. Today they are recognized...
Astronomy & Space The invisible boundaries that surround planets in space
IntroductionPlanets are not just solid balls orbiting the Sun. Around each planet exist invisible regions that shape its...
Astronomy & Space What lies beneath the clouds of the giant planets?
IntroductionThe giant planets—Jupiter, Saturn, Uranus, and Neptune—are famous for their dramatic cloud tops. But what li...
Astronomy & Space What creates giant cracks across the surfaces of icy moons?
IntroductionMany icy moons in the outer Solar System display long, dramatic cracks and ridges across their frozen surfac...
Astronomy & Space How stars can keep shining for billions of years
IntroductionStars can shine for billions of years because they convert mass into energy through nuclear fusion in a stea...