Prompt: Earth's natural satellite
ScienceA little curiosity
Space object · RECALLEarth's natural satelliteThink it. Then flip it.
☼Science
Science · Editorial deck
Solar System & Beyond
Planets, moons and landmarks
Your path through the deck
Learn it chapter by chapter.
Start with a chapter that catches your eye, or mix a few together in your round.
- 01Moons and eclipses11 cards · ~2 min
- 02Small bodies and distant space11 cards · ~2 min
- 03Planets and their orbits29 cards · ~5 min
- 04The Sun and observing space5 cards · ~1 min
Taste it
Three cards to begin.
Prompt: Largest moon in the solar system
ScienceA little curiosity
Space object · RECALLLargest moon in the solar systemThink it. Then flip it.
Prompt: Moon with a thick nitrogen atmosphere
ScienceA little curiosity
Space object · RECALLMoon with a thick nitrogen atmosphereThink it. Then flip it.
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The questions inside.
01Earth's natural satelliteRECALL
02Largest moon in the solar systemRECALL
03Moon with a thick nitrogen atmosphereRECALL
04This icy Galilean moon, the second outward from Jupiter, is a major target in the search for a subsurface ocean.RECALL
EuropaEuropa's likely ocean lies beneath an icy crust. Other moons also have subsurface oceans, so that clue alone does not identify it.
Share this card ↗Source: Europa (moon) ↗05The Moon's changing phases · explain why its apparent illuminated shape changes through the monthRECALL
As the Moon orbits Earth, we see different fractions of its sunlit half.Ordinary lunar phases are not caused by Earth's shadow. That shadow is involved in a lunar eclipse.
Share this card ↗Source: Solar System ↗06Solar eclipse · relative positions of the Sun, Earth and MoonRECALL
The Moon passes between Earth and the SunIts shadow falls on Earth
Share this card ↗Source: Solar System ↗07Lunar eclipse · relative positions of the Sun, Earth and MoonRECALL
Earth passes between the Sun and the MoonEarth's shadow falls on the Moon
Share this card ↗Source: Solar System ↗08This synchronized rotation and orbit keeps the same side of the Moon facing Earth.RECALL
09This moon is the most volcanically active.RECALL
10This icy Saturnian moon shoots plumes from its south polar region, fed by a subsurface ocean.RECALL
11NASA's Clipper mission, launched in 2024, is bound for this icy moon of Jupiter.RECALL
EuropaEuropa Clipper will investigate whether conditions beneath Europa's icy surface could support life; it is not a direct life-detection…
Share this card ↗Source: Europa (moon) ↗12Dwarf planet in the asteroid beltRECALL
13Boundary where the solar wind meets interstellar spaceRECALL
14The Sun · stellar spectral class and evolutionary stageRECALL
G-type main-sequence starIt is also called a yellow dwarf
Share this card ↗Source: G-type main-sequence star ↗15This main region of rocky minor bodies lies between Mars and Jupiter.RECALL
16This belt beyond Neptune contains icy bodies including Pluto.RECALL
17This proposed distant, roughly spherical cloud supplies many long-period comets.RECALL
18This small icy body develops a coma and sometimes a tail as it approaches the Sun.RECALL
19This small rocky or metallic body travels through space, before any atmospheric entry.RECALL
20This streak of light appears when a space rock enters an atmosphere.RECALL
21This name identifies a space rock that survives atmospheric entry and reaches the ground.RECALL
22This vast canyon system stretches across Mars near its equator.RECALL
23Mercury · position among the eight planets, counting outward from the SunRECALL
24Venus · position among the eight planets, counting outward from the SunRECALL
25Earth · position among the eight planets, counting outward from the SunRECALL
26Mars · position among the eight planets, counting outward from the SunRECALL
27Jupiter · position among the eight planets, counting outward from the SunRECALL
28Saturn · position among the eight planets, counting outward from the SunRECALL
29Uranus · position among the eight planets, counting outward from the SunRECALL
30Neptune · position among the eight planets, counting outward from the SunRECALL
31Largest planet in our Solar SystemRECALL
32Hottest planet in our Solar SystemRECALL
33Solar System planet with the Great Red SpotRECALL
34Solar System planet with the shortest orbital yearRECALL
35Solar System planet with the longest orbital yearRECALL
36Planet known for Olympus MonsRECALL
37This volcano on Venus showed a changing vent in 1991 Magellan radar images, reported in 2023.RECALL
Maat MonsThe radar images show a vent changing shape and size. Some dramatic 3D views exaggerate vertical relief, so they should not be read as…
Share this card ↗Source: NASA: volcanic activity on Venus ↗38This planet is the smallest in the Solar System.RECALL
39This planet takes longer to rotate once relative to the stars than to orbit the Sun.RECALL
VenusVenus's sidereal rotation takes about 243 Earth days and its year about 225. Its sunrise-to-sunrise solar day is about 117 Earth days;…
Share this card ↗Source: Venus ↗40This tilt relative to Earth's orbital plane is the main reason for the seasons.RECALL
Earth's axial tiltThe tilt changes the angle of sunlight
Share this card ↗Source: Earth's axial tilt ↗41This reddish iron compound gives much of Mars's surface its colour.RECALL
42This planet is the largest in the Solar System.RECALL
43Saturn's prominent rings · the two main types of materialRECALL
Ice and rock particlesThe particles range from dust to boulders
Share this card ↗Source: Rings of Saturn ↗44This planet has an extreme axial tilt and rotates on its side.RECALL
45This planet has the fastest winds measured in the Solar System.RECALL
46This attractive force keeps planets in orbit around the Sun.RECALL
47This distance unit is based on the Earth–Sun separation and is defined as exactly 149,597,870,700 metres.RECALL
48This term names a planet orbiting a star other than the Sun.RECALL
49Under the IAU Solar System definition, this body orbits the Sun, is nearly round and has cleared its orbital neighbourhood.RECALL
50This enormous shield volcano on Mars is the tallest widely recognized volcano in the Solar System.RECALL
51This large infrared space telescope launched in December 2021 and observes near the Sun–Earth L2 point.RECALL
52This visible surface layer of the Sun produces most of the light we see.RECALL
53This central region of the Sun produces energy through nuclear fusion.RECALL
54This stream of charged particles flows outward from the Sun.RECALL
55This astronomical distance unit equals the distance light travels in one year.RECALL
56This region around a star could permit liquid water on a planet's surface under suitable atmospheric conditions.RECALL
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