Our Place in the Solar System – Vocabulary Flashcards (Grade 7)

Vocabulary flashcards covering key concepts from the lecture notes: the Solar System, planets, moons, eclipses, tides, rotation/revolution, seasons, and related terms.

Sun

The center of the Solar System; a massive ball of hydrogen and helium that provides light and heat and governs the orbits of planets.

Solar System

The Sun and all objects that orbit it, including eight planets, moons, dwarf planets, asteroids, and comets.

Mercury

Closest planet to the Sun; smallest planet; very thin atmosphere; extreme day–night temperatures and heavily cratered surface.

Venus

Second planet from the Sun; hottest planet due to a thick carbon dioxide atmosphere and a strong greenhouse effect.

Earth

Third planet; supports life; atmosphere rich in nitrogen and oxygen; has liquid water and diverse environments.

Mars

Fourth planet; the Red Planet; thin carbon dioxide atmosphere; features include Olympus Mons and Valles Marineris; polar ice caps.

Jupiter

Largest planet; Great Red Spot; bands of clouds; many moons, including Galilean moons Io, Europa, Ganymede, and Callisto.

Saturn

Second-largest planet; famous for its rings; many moons, including Titan.

Uranus

Ice giant with an axial tilt of about 98 degrees; rotates on its side; notable for extreme seasons and a blue color.

Neptune

Farthest planet from the Sun; deep blue, very strong winds; faint ring system; multiple moons including Triton.

Asteroid Belt

Region between Mars and Jupiter filled with rocky/metallic bodies; remnants from the early solar system that did not form a planet.

Dwarf Planet

A celestial body that orbits the Sun, is nearly round, but has not cleared its orbital path of other debris.

Pluto

Dwarf planet in the Kuiper Belt; once considered the ninth planet; has several moons.

Terrestrial Planets

Rocky, solid planets in the inner Solar System: Mercury, Venus, Earth, and Mars.

Gas Giants

Large planets without solid surfaces; composed mainly of hydrogen and helium; include Jupiter, Saturn, Uranus, and Neptune.

Mass

The amount of matter in an object; remains constant regardless of location.

Weight

The force of gravity on a mass; varies with the strength of a planet’s gravity.

Gravity

The attractive force between masses; keeps planets in orbit and gives objects weight.

Rotation

Spinning of a planet around its own axis; Earth rotates from west to east; ~24 hours defines a day.

Day and Night

The cycle of daylight and darkness caused by a planet’s rotation.

Revolution

The orbit of a body around another body (e.g., Earth around the Sun); about 365.25 days for Earth.

Axis Tilt

The tilt of Earth’s axis (~23.5 degrees) that affects sunlight angle and seasonal patterns.

Seasons

Spring, Summer, Autumn (Fall), and Winter; caused by axial tilt and orbital position.

Solstice

Two yearly moments: Summer Solstice (longest day) and Winter Solstice (shortest day); Sun’s path is at its extreme.

Equinox

Two yearly moments: Vernal (Spring) and Autumnal (Fall); day and night are approximately equal in length.

Equator

Zero latitude line around the middle of Earth; regions near it have less seasonal variation.

Tropics of Cancer and Capricorn

Latitudinal boundaries where the Sun is directly overhead at solstices (Cancer in June, Capricorn in December).

Moon Phases

Eight major appearances of the Moon as seen from Earth: New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter, Waning Crescent.

New Moon

Moon between Earth and Sun; the side facing Earth is not illuminated; not visible.

Waxing Crescent

A small sliver of the Moon becomes visible after new moon; illuminated portion grows on the right.

First Quarter

Half of the Moon is illuminated; right half is bright; Sunlit side is to the east.

Waxing Gibbous

More than half of the Moon is illuminated and increasing; visible in afternoon/evening.

Full Moon

Moon opposite the Sun with its entire face illuminated; rises at sunset and sets at sunrise.

Waning Gibbous

Illuminated portion decreases from the right; Moon visible late at night and into the morning.

Third Quarter (Last Quarter)

Half of the Moon is illuminated; left half is bright; rises around midnight.

Waning Crescent

A small crescent visible in the early morning before sunrise; illuminated from the left.

Lunar Cycle

Complete sequence of Moon phases lasting about 29.5 days; also called a lunar month.

Tides

Regular rise and fall of ocean levels caused mainly by the Moon’s gravity, with help from the Sun.

Spring Tides

Higher high tides and lower low tides that occur during new and full moons.

Neap Tides

Lower high tides and higher low tides that occur during the first and third quarters.

Umbra

The darkest, central part of a shadow; in solar eclipses, the region where the Sun is completely blocked by the Moon.

Penumbra

The lighter, outer part of a shadow; in solar eclipses, partial obscuration of the Sun.

Solar Eclipse

Moon moves between Earth and Sun, blocking all or part of the Sun’s light; types include Total, Partial, and Annular.

Lunar Eclipse

Earth moves between Sun and Moon, casting a shadow on the Moon; types include Total, Partial, and Penumbral.

Galilean Moons

Io, Europa, Ganymede, and Callisto—the four largest moons of Jupiter.

Triton

Neptune’s largest moon; known for geysers that eject nitrogen gas.

Great Red Spot

A colossal, long‑lasting storm on Jupiter, larger than Earth.

Kuiper Belt

A region beyond Neptune’s orbit containing many small icy bodies and dwarf planets, including Pluto.

Light Year

The distance that light travels in one year; about 9.46 trillion kilometers.

International Space Station (ISS)

A multinational space station serving as a laboratory and a hub for international cooperation in space exploration.

Artificial Satellite

Human-made object placed into orbit around Earth for communication, weather monitoring, navigation, or research.