The Solar System and Astronomy

Fill-in-the-blank practice flashcards covering solar system concepts, astronomy history, planetary movements, and cosmic scales.

Scientists who study objects seen in the sky are called __________

astronomers

Until the 16th century, people believed Earth was at the center of the universe, an idea called the __________ world view.

geocentric

Italian astronomer __________ used specialized telescopes on stands to study the night sky in detail.

Galileo Galilei

The distance from Earth to the Moon is approximately __________

$$380\,000\,\text{km}$$

The world view that Earth and the other planets revolve around the Sun is called the __________ world view.

heliocentric

An object that circles in an orbit around a planet is called a __________

satellite

The space telescope launched in the year __________ that orbits outside Earth's atmosphere is Hubble.

$$1990$$

One meter was defined by dividing the distance from the Equator to the North Pole into __________ equal parts.

$$10\,\text{million}$$

Earth travels in its orbit around the Sun at a speed of __________

$$100\,000\,\text{km/h}$$

A complete orbit of Earth around the Sun takes $365$ days and __________

$$6\,\text{hours}$$

To adjust for the extra hours in Earth's orbit, a leap year containing __________ days occurs every fourth year.

$$366$$

Earth rotates around its own axis, which is tilted by __________

$$23^\circ$$

The shortest day of the year is called the __________ and occurs around December $22$

winter solstice

The duration from one full moon to the next full moon is __________

$$29.5\,\text{days}$$

When the Moon passes directly between the Sun and Earth, a __________ occurs.

solar eclipse

Astronomer __________ discovered that planetary orbits around the Sun are oval-shaped (elliptical).

Johannes Kepler

The planet closest to the Sun, which is also the smallest planet in the solar system, is __________

Mercury

Surface temperatures on Venus can reach above __________

$$500\,^\circ\text{C}$$

Mercury, Venus, Earth, and Mars have solid surfaces and are known as __________ planets.

terrestrial

Jupiter, Saturn, Uranus, and Neptune are massive planets made of gas and are called __________ planets.

gas

In the year __________, astronomers reclassified Pluto as a dwarf planet.

$$2006$$

A space rock that enters Earth's atmosphere, slows down, and glows is called a __________

meteor

If a space rock survives its flight through the atmosphere and reaches Earth's surface, it is called a __________

meteorite

Light travels through space at a speed of __________ per second.

$$300\,000\,\text{km}$$

A light-year is defined as the __________ that light travels in one year.

distance

The time it takes for the Milky Way galaxy to complete one full rotation is called a galaxy year, which corresponds to __________

$$240\,\text{million years}$$

The distance from Earth to the Andromeda galaxy is approximately __________ light-years.

$$2.2\,\text{million}$$

Scientists believe the universe was created over $13$ billion years ago in a huge explosion called the __________

Big Bang

Celestial body

Any natural object in space that exists outside of Earth's atmosphere.

Constellation

A pattern of stars.

The Big Dipper

Asterism formed by seven bright stars in the northern night sky.

Geocentric view

An Earth-centered view of the Solar System.

Heliocentric view

A Sun-centered view of the Solar System.

Telescope

An instrument that helps astronomers look at distant stars.

Hubble Space Telescope

A telescope that studies deep space and has helped calculate the age of the universe.

Earth's rotation

The spinning of Earth around its own axis, causing day and night.

Earth's revolution

The movement of Earth around the Sun, taking about 365.25 days.

Leap year

Occurs every four years to compensate for the extra hours in Earth's orbit.

Seasons

Caused by the tilt of Earth's axis as it orbits the Sun.

Rocky planets

The four planets: Mercury, Venus, Earth, and Mars.

Giant planets

The four gas planets: Jupiter, Saturn, Uranus, and Neptune.

Dwarf planet

A small celestial body that orbits the Sun and shares its orbital area with other objects.

Pluto classification

Pluto is classified as a dwarf planet.

Light-year

A measurement of the distance that light travels in one year.

Galaxy

A large group of stars, gas, and dust bound together by gravity.

Milky Way

The galaxy that contains our Solar System.