Planets
Seasons on Earth and Mars: Orbits and Climate
A Martian year lasts 687 Earth days, and Mars’s orbital eccentricity is about five times Earth’s—so its seasons are uneven in length.
✦ PlanetsSaturn and Its Moons: Titan, Enceladus, and Other Worlds
Titan hides methane lakes beneath its dense atmosphere, while Enceladus ejects water vapor and ice. We compare the composition and activity of Saturn’s moons.
✦ PlanetsEarth and Mars: Comparing Their Internal Structure
Mars’s core radius is estimated at 1,780–1,810 km, while Earth’s mantle extends 2,890 km. Their interiors help explain each planet’s geology.
✦ PlanetsMercury and Venus Near the Horizon: When to Look for Them
Mercury never strays more than 28° from the Sun, so look for it at twilight. Learn whether to choose morning or evening—and why location and a clear horizon mat
✦ PlanetsWhy Mars Is Brighter at Opposition
At opposition, Earth passes between the Sun and Mars, bringing the planet closer and making it appear larger and brighter. But not all oppositions are alike.
✦ PlanetsPlanets: Names, Myths, and How Their Worlds Differ
Planet names come from Roman gods, except for Earth. Explore how the eight worlds differ and which gases make up their atmospheres.
✦ PlanetsPlanets in Space: Finding and Analyzing Atmospheres
Planets are found through transits, stellar wobbles, and direct imaging. Spectroscopy helps detect water, sodium, and other molecules in their atmospheres.
✦ PlanetsPlanets in Order: Their Sequence from the Sun
The planets in order from Mercury to Neptune: the eight worlds, their positions from the Sun, and why Pluto is not included in the list.
✦ PlanetsIZH Planeta: A Motorcycle, Not a Celestial Body
IZH Planeta is the name of a Soviet motorcycle, not an astronomical object. Learn how to tell the IZH motorcycle series apart from Solar System planets.
✦ PlanetsWhat to Look for in Planetary Atmosphere Composition
The biochemical composition of planetary atmospheres is more than a list of gases. Explore Solar System worlds, biosignatures, and the limits of interpretation.
✦ PlanetsTemperatures and Characteristics of Jupiter and Saturn
A review of the temperature profiles of Jupiter and Saturn, analyzing how mass, atmosphere, and orbital resonances impact the climate of these gas giants.
✦ PlanetsHow Exoplanet Mass and Composition Affect Their Atmospheres
A planet's mass and composition directly shape its atmosphere's type and properties, influencing climate and habitability across diverse exoplanets.