Question 1 of 14Correct: 0
Why is a day on Mercury longer than a year?
What was believed about Mercury before the 1960s?
What changed in 2006?
Which condition does Pluto not meet?
Why is Venus hotter than Mercury, even though it's farther from the Sun?
Why didn't Venus's carbon dioxide get locked away in rocks?
Why don't chunks near Saturn come together to form a moon?
Why might Saturn's rings be a temporary phenomenon?
Why are the seasons at Uranus's poles so long?
What do the moons and rings suggest about Uranus's tilt?
Why does Jupiter's Red Spot resist breaking apart for so long?
Why doesn't Jupiter's storm die out like a hurricane on Earth?
What lies beneath a gas giant's clouds?
How long did the probe last in the atmosphere?
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Answers and explanations14 questions
- Why is a day on Mercury longer than a year? The planet rotates slowly on its axis but moves quickly in orbitAbout 176 Earth days pass from sunrise to sunrise there, which is two local years.From “Why a Day on Mercury Is Longer Than a Year”
- What was believed about Mercury before the 1960s? That it keeps the same side facing the SunRadar measurements corrected the mistake by showing that Mercury rotates slowly.From “Why a Day on Mercury Is Longer Than a Year”
- What changed in 2006? The definition of a planet changedSimilar bodies were found beyond Neptune's orbit, and the choice was between a new rule and a growing list of planets.From “Why Pluto Stopped Being a Planet”
- Which condition does Pluto not meet? It has not cleared the area around its orbitThousands of objects of comparable origin move nearby, so Pluto is not the dominant body in its region.From “Why Pluto Stopped Being a Planet”
- Why is Venus hotter than Mercury, even though it's farther from the Sun? Its dense atmosphere traps heatVenus has a dense carbon dioxide atmosphere: light gets down, but infrared heat struggles to escape.From “Why Venus Is Hellishly Hot”
- Why didn't Venus's carbon dioxide get locked away in rocks? Water vanished, so nothing could bind carbonOn Earth, rain and oceans bind carbon in limestone, but Venus lost its water and that pathway closed.From “Why Venus Is Hellishly Hot”
- Why don't chunks near Saturn come together to form a moon? The planet's gravity pulls them apart more stronglyNear the planet, differences in its gravity tear the debris cluster apart, preventing it from becoming a moon.From “Why Saturn Has Rings”
- Why might Saturn's rings be a temporary phenomenon? Material from the rings gradually falls onto the planetRing particles gradually fall onto Saturn, so the rings may eventually disappear.From “Why Saturn Has Rings”
- Why are the seasons at Uranus's poles so long? Its axis lies almost in the plane of its orbitBecause the axis lies almost flat, the poles take turns facing the Sun or remaining in darkness for a long time.From “Why Uranus Lies on Its Side”
- What do the moons and rings suggest about Uranus's tilt? The tilt appeared early, while a disk of material remainedThe moons and rings are tilted along with the planet, so they formed around Uranus after it had already tilted.From “Why Uranus Lies on Its Side”
- Why does Jupiter's Red Spot resist breaking apart for so long? Countercurrents and small storms keep feeding itCountercurrents spin up the vortex, while small storms give it their energy.From “What Is That Spot on Jupiter”
- Why doesn't Jupiter's storm die out like a hurricane on Earth? Jupiter has no shore or solid surfaceJupiter has no land or terrain for a hurricane to lose its fuel against and break apart.From “What Is That Spot on Jupiter”
- What lies beneath a gas giant's clouds? A gradual transition from gas to denser statesThere is no sharp boundary: one state of matter gradually changes into another.From “Do Gas Giants Have a Solid Surface?”
- How long did the probe last in the atmosphere? About an hourIt reached only a small depth by planetary standards before being destroyed.From “Do Gas Giants Have a Solid Surface?”