Astronomy Test
Number of planets in our solar system
8
Dwarf planets
A mass in space that does not fit the classification of a planet or a moon. Cerus, Pluto, hamuea, makemake, Eris
Meteorite
A meteorite or asteroid that passes through earth's atmosphere and lands on earth's surface
Solar system
A star and everything that revolve around it
Supernova
A stellar explosion that formed our solar system. A cloud of spinning dust and gas contracted due to gravity forming the sun in the center.
Mass
Amount of matter of the object compared to the earths matter
Period of revolution
Amount of time to move around the sun one time
Period of rotation
Amount of time to spin one time
Comet
An object made of ice and rock fragments that revolves around the sun usually in a highly eccentric orbit. Most of these originate in the kuiper belt which is past the orbit of Neptune. When this approaches the sun, the icy surface evaporated and caused the dusts and gases to glow as a bright tail. The solar wind pushes the tail away from the sun
Planet
Any object that directly revolves around a star, has a nearly round shape, and has its own orbital zone
Mean distance from the sun
Average distance in millions of kilometers from the sun
Which planet has the greatest density
Earth
Uranus
First planet discovered with a telescope in 1781. Has a rotational axis tilted to nearly 90° so it seems to spin on its side. Has at least 27 moons
Asteroids
Irregularly shaped rock that is smaller than a planet and occupies in orbit around the sun. Found in the asteroid belt between the orbits of mars and Jupiter
Which planet has the greatest equatorial diameter
Jupiter (142,984 KM)
Which planet has the greatest mass
Jupiter (317.83)
Which planet has the shortest period of rotation
Jupiter (9 hours, 50 minutes, 30 seconds)
Jupiter
Largest planet in the solar system. Made largely of hydrogen and helium gas. Giant red spot visible in the surface is a huge storm that lasted 300 years. Has at least 63 moons. four major moons, were discovered by Galileo and provided evidence that not all objects move around earth
Which planet has a period of revolution twice the earths period of revolution
Mars
Which planet has a period of rotation closest to the period of rotation for earth
Mars
Which planet is approximately half the size of earth
Mars
Which planet has the greatest eccentricity
Mercury
Which planet has the smallest mass
Mercury
Which planet has the smallest equatorial diameter
Mercury (4,879 km
Which planet is closest to the sun
Mercury (57.9 million km)
Which planet has the shortest period of revolution
Mercury (88 Days)
Planet criteria
Must orbit the sun, must have a nearly round shape, must have its own orbital zone (cause of Pluto no longer being a planet and being classified as a dwarf planet)
Which plant has the longest period of revolution
Neptune (164.8 years)
Which planet is farthest from the sun
Neptune (4.498.3 million km)
Venus
Often called Earth's "sister" planet because it is similar in size but is extremely hot and has clouds made of sulfuric acid. After earths moon, it is the brightest object in the night sky. Had no moons and has the roundest shaped orbit
Earth
Only planet known to have liquid water and life, largest and densest terrestrial planet, has one moon
Jovian planet
Outer four planets: Jupiter, Saturn, Uranus, Neptune. Large diameters and low densities
Meteoroids
Particles of rock and metal in space ranging in size from a grain of sand to a large boulder. Always smaller than asteroids (less than 1km in diameter)
Mars
Red colored planet because of iron dioxide is prevalent on the surface. Conditions are closest to the favorable conditions of life. Has surface features that were likely formed by running water in the past, but there is currently no liquid water on the Martian surface. Has two moons
Terrestrial planets
Rocky, small, high density, and Earth like planets. Inner four planets: mercury, Venus, earth, mars
Which planet has the lowest density
Saturn
Which planet is approximately 10 times farther from the sun than the earth is from the sun
Saturn
Saturn
Second largest planet in the solar system. Has rings that can be seen from Earth using binoculars. Has the lowest density of all the planets. Has at least 62 moons
Neptune
Second planet discovered with a telescope. Was predicted to exist using mathematical calculation before it was actually seen with a telescope in 1846. Has at least 14 moons. Has completed less than one orbit of the sun in the last 100 years
Eccentricity of orbit
Shape of the orbit around the sun
Greenhouse effect
Short wave visible light enters through the greenhouse glass, the surface absorbs the light and heats up. The long wave infrared heat released by the surface gets trapped by carbon dioxide. The planets temperature increases
Equatorial diameter
Size of the planet at the equator
Meteor
Streak of light produced when a meteoroid enters earth's atmosphere and burns due to friction of gas molecules. Commonly known as a shooting star
Our ___ is the center of the solar system
Sun
Density
The amount of matter in the given space of the object
Planetesimals
The dust and gas left outside clumped together to form this. They collided and formed planets
Retrograde motion
The motion exhibited by planets when they appear to move backward for a time in comparison to the stars caused by differences in revolution around the sun
Mercury
Travel through our sky and around the sun so quickly. Closest planet to the sun. Has no atmosphere and no moons. Has the most elliptical (oval) shaped orbit
List of Jovian planets in order of increasing mass
Uranus, Neptune, saturn, Jupiter
Which planet has the lowest eccentricity
Venus
Which planet has the longest period of rotation
Venus (243 days)
Planet with the highest surface temperature and why
Venus is the hottest planet due to the greenhouse effect. Venus' atmosphere is 95% carbon dioxide, a major greenhouse gas
Impact crater
When very large meteorites strike earth's surface, they form circular depression in the ground
