How many natural satellites does Earth have?: One, the Moon How long does the Moon take to orbit Earth?: About 27 days; phases repeat about every 29.5 days Phases of the Moon: The changing shapes of the lit part of the Moon we see New moon: The Moon is not visible because its lit side faces away Waxing crescent: A growing sliver of the Moon First quarter: Half the Moon is lit, the right half in the Northern Hemisphere Waxing gibbous: More than half lit and growing Full moon: The whole face of the Moon is lit Waning gibbous: More than half lit and shrinking Third (last) quarter: Half the Moon is lit, the left half in the Northern Hemisphere Waning crescent: A shrinking sliver of the Moon Why does the Moon have phases?: We see different amounts of its sunlit half as it orbits Earth Does the Moon make its own light?: No; it reflects sunlight Lunar eclipse: Earth's shadow falls on the Moon Solar eclipse: The Moon passes between the Sun and Earth, blocking sunlight Total solar eclipse: The Moon completely covers the Sun's disk Is it safe to look at a solar eclipse without eye protection?: No; use special eclipse glasses Corona: The Sun's outer atmosphere, seen during a total eclipse Craters on the Moon come from: Impacts of asteroids and meteoroids Maria (lunar seas): Dark, flat plains of ancient lava on the Moon Who first walked on the Moon?: Neil Armstrong in 1969 Which mission landed first humans on the Moon?: Apollo 11 How many Apollo missions landed people on the Moon?: Six Gravity on the Moon compared to Earth: About one-sixth Why does the same side of the Moon always face Earth?: It rotates once for each orbit (tidal locking) Moon landing year of the last Apollo mission: 1972, Apollo 17 Largest moon in the solar system: Ganymede, a moon of Jupiter Galilean moons: Io, Europa, Ganymede and Callisto, found by Galileo in 1610 Io: A volcanic moon of Jupiter Europa: An icy moon of Jupiter with an ocean beneath its ice Titan: Saturn's largest moon, with a thick atmosphere and lakes of methane Enceladus: A small icy moon of Saturn that sprays water ice from its south pole Phobos and Deimos: The two small moons of Mars Triton: Neptune's largest moon, which orbits backward Charon: The largest moon of Pluto Miranda: A moon of Uranus with cliffs and grooves Titania: The largest moon of Uranus Callisto: A heavily cratered moon of Jupiter Mimas: A small icy Saturn moon with one huge crater Sun: A star made mostly of hydrogen and helium Sun's age, about: 4.6 billion years Sun's surface temperature, about: 5,500 degrees Celsius Sun's core temperature, about: 15 million degrees Celsius What powers the Sun?: Nuclear fusion of hydrogen into helium How long does sunlight take to reach Earth?: About 8 minutes Sunspot: A cooler, darker area on the Sun's surface Solar flare: A sudden burst of energy from the Sun Solar wind: A stream of charged particles flowing from the Sun Aurora: Glowing lights in the sky from solar particles hitting the atmosphere Photosphere: The visible surface of the Sun Solar system formed from: A cloud of gas and dust about 4.6 billion years ago Earth's rotation period: About 24 hours Earth's orbit period: About 365.25 days Leap year: A year with an extra day, February 29, to fix the calendar Why do we have day and night?: Earth rotates on its axis Summer in the Northern Hemisphere happens when: The Northern Hemisphere tilts toward the Sun Satellite: An object that orbits a planet Tidal force: The Moon's gravity tugging on Earth's oceans Supermoon: A full moon at its closest point to Earth, looking larger Blue moon: The second full moon in one calendar month Harvest moon: The full moon nearest the autumn equinox Free flashcards from Peabody at peabody.kids/flashcards/space-moons-sun-earth