Solar System Facts & Worksheets

The solar system comprises orbiting components with the sun that are gravitationally coupled. It was created by the gravitational breakdown of a massive interstellar molecular cloud 4.6 billion years ago. The sun contains the majority (99.86%) of the system’s mass, with Jupiter containing most of the remaining group. The four planets of the inner system – Mercury, Venus, Earth, and Mars – are terrestrial planets made mostly of rock and metal. The four giant planets of the outermost system are significantly more extensive and more noticeable than the terrestrials. Jupiter and Saturn are gas giants, made mostly of hydrogen and helium; Uranus and Neptune are ice giants, composed predominantly of volatile substances with comparatively high melting points compared to hydrogen and helium, such as water, ammonia, and methane.

See the fact file below for more information on the Solar System or alternatively, you can download our 24-page Solar System worksheet pack to utilise within the classroom or home environment.

Key Facts & Information

STRUCTURE AND COMPOSITION

• The term solar comes from the Latin word sol, which means “about the sun.”
• The sun is the solar system’s primary gravitational component, and its planetary system is kept relatively stable and slowly developing by completing isolated gravitationally constrained orbits around the sun.

ORBITS

• The planets and other massive objects in transit around the sun are close to the ecliptic, the plane of Earth’s orbit.
• Smaller ice objects, like comets, frequently circle at much larger inclinations than this plane. Several planets in the Solar System have their secondary systems, which are orbited by natural satellites known as moons.
• Many giant natural satellites rotate in synchronous orbit, with one face always towards their parent. Planetary rings are narrow bands of tiny particles that circle the four giant planets in tandem.
• Planets and most other objects circle the sun in the same direction as the sun rotates as a byproduct of the solar system’s development. That is, clockwise as seen from above the Earth’s north pole. There are certain exceptions, including Halley’s Comet.
• Most of the more giant moons orbit their planets in a prograde direction, mirroring the planetary rotation; Neptune’s most giant moon, Triton, circles in the opposite, retrograde direction.
• Most oversized objects revolve about their axes in prograde motion related to their orbit, except Venus, which rotates in the reverse direction.
• Planetary orbits are nearly circular, although several comets, asteroids, and Kuiper belt objects have very eccentric orbits.
• Kepler’s rules only account for the sun’s gravitational attraction to an orbiting planet, not the gravitational forces of several bodies on one another.

COMPOSITION

• The sun, four smaller inner planets bordered by a belt of predominantly rocky asteroids, and four massive planets encircled by the Kuiper belt of mostly frozen objects comprise the general structure of the documented parts of the Solar System.
• Astronomers may arbitrarily split this structure into distinct sections. The asteroid belt and the four terrestrial planets comprise the inner Solar System, and the outer Solar System includes the four giant planets and asteroids.
• Since the discoveries of the Kuiper belt, the Solar System’s farthest regions have been regarded as discrete zone comprising objects past Neptune, the sun is the Solar System’s primary component. 
• This low-mass star dominates it gravitationally and includes 99.86% of the system’s known mass. The giant planets, the sun’s four largest circling entities, composed 99% of the remaining group, with Jupiter and Saturn accounting for more than 90%.
• The remaining objects in the Solar System (the four terrestrial planets, exoplanets, satellites, asteroids, and comets) constitute less than 0.002% of the total weight of the Solar System.

FORMATION AND EVOLUTION

• The Solar System began from the gravitational collapse of an area within a massive molecular cloud 4.6 billion years ago. This first cloud was likely light-years broad and gave birth to multiple stars.
• This cloud was primarily hydrogen, as is characteristic of molecular clouds, with some helium and trace quantities of heavier elements fused by past generations of stars. Compressed angular momentum conservation forced it to revolve faster than the pre-solar nebula, or area that would form the Solar System.
• The planets were produced by the accretion of dust and gas from this disc, which gravitationally pulled each other and merged to form increasingly more enormous masses. There may have been hundreds of protoplanets in the earliest Solar System, but they either combined or were destroyed or expelled, leaving the planets, dwarf planets, and minor bodies.
• Due to their higher boiling temperatures, only metals and silicates could live in solid form in the heated inner solar system near the sun. They would ultimately create the terrestrial planets of Mercury, Venus, Earth, and Mars.
• Because metallic elements were such a tiny component of the solar nebula, rocky planets could not develop to be massive. Jupiter, Saturn, Uranus, and Neptune originated further out, beyond the freezing point of water, which is the temperature difference between Mars and Jupiter’s orbits at which volatile ice compounds freeze.
• These planets’ ices were more common than the metals and silicates that produced the terrestrial inner planets, permitting them to become huge enough to catch enormous atmospheres of the lightest and most abundant elements, hydrogen and helium.
• The asteroid belt, Oort cloud, and Kuiper belt gathered leftover material that never formed planets.

SUN

• The sun is the star of the Solar System and by far its most enormous component. Its massive mass (332,900 Earth masses), which accounts for 99.86% of all groups in the Solar System, generates core temperatures and densities high enough to support the nuclear fusion of hydrogen into helium.
• It generates massive energy, primarily emitted into space as electromagnetic energy with a visible light peak.
• The sun is a main-sequence star because it combines hydrogen into helium at its core. It is a G2-type main-sequence star, with the type classification referring to its effective temperature.
• Hotter main-sequence stars are brighter, and the sun’s temperature is halfway between the temperatures of the most desirable and coldest stars. Stars that are hotter and more brilliant than the sun are uncommon, but red dwarfs, far dimmer and harder, account for over 75% of the stars in the Milky Way.

INNER SOLAR SYSTEM

• The inner Solar System includes the rocky planets and the asteroid belt. The objects of the internal solar system, primarily silicates and metals, are pretty near the sun; the radius of this entire region is smaller than the distance between Jupiter and Saturn’s orbits.
• This area is also near the frost line, around 5 AU (750 million km; 460 million mi) from the sun.

INNER PLANETS

• The four terrestrial or inner planets are solid, stony material, have few or no moons, and have no ring systems. They are mostly made up of refractory materials like silicates, their crusts and mantles, and metals like iron and nickel, which make up their cores.
• Venus, Earth, and Mars have giant atmospheres to support weather, and they all contain impact craters and tectonic surface features like rift valleys and volcanoes.
• Inner planets should not be confused with inferior planets, which are planets closest to the Sun than Earth (i.e., Mercury and Venus).

MERCURY

• Mercury is the sun’s closest neighbor (0.4 AU) (60 million km; 37 million mi).
• Mercury is the Solar System’s most minor planet (0.055 MEarth) and has no natural satellites.
• The most prominent geological features include impact craters or basins with ejecta blankets, the remnants of early volcanism, including magma flows, and lobed ridges or rupes, which were most likely formed during a time of contraction early in the planet’s history.

VENUS

• Venus (0.7 AU (100 million kilometers; 65 million mi) from the sun) is similar in size to Earth (0.815 MEarth) and has a thick silicate mantle surrounding an iron core, a significant atmosphere, and indications of internal geological activity.
• It is significantly drier than Earth, with a ninety-fold denser atmosphere. There are no natural satellites of Venus. Because of the concentration of greenhouse gases in the atmosphere, it is the warmest planet, with surface temperatures reaching 400 ° C. (752 degrees Fahrenheit).

EARTH

• Earth is the biggest and densest of the inner planets, the only one considered to have current geological activity, and the only location where life is known to exist (1 AU (150 million km; 93 million mi) from the sun). It contains the sole liquid hydrosphere among the terrestrial planets, and plate tectonics have been seen.
• The atmosphere of Earth differs dramatically from that of the other planets, transformed by the advent of life to include 21% free oxygen.
• The planetary magnetosphere protects the surface from solar and cosmic radiation, reducing atmospheric stripping and keeping the planet habitable. It has one natural satellite, the moon, the Solar System’s only big satellite of a terrestrial planet.

MARS

• Mars is smaller than both Earth and Venus (1.5 AU (220 million kilometers; 140 million mi) from the sun (0.107 MEarth).
• It has a central carbon dioxide atmosphere with a surface pressure of 6.1 millibars (0.088 psi; 0.18 inHg), which is about 0.6% of Earth yet adequate to sustain weather occurrences.
• Its landscape, dotted with volcanoes like Olympus Mons and rift valleys like Valles Marineris, reveals the geological activity that may have lasted as recently as 2 million years ago.
• Its red tint is caused by the soil’s iron oxide (rust). Mars has two natural satellites (Deimos and Phobos) that are assumed to be trapped asteroids or ejected debris from a significant impact early in Mars’s history.

ASTEROID BELT

• Asteroids, except Ceres, are tiny Solar System asteroids comprised primarily of refractory stony and metallic materials, with some ice. They have sizes varying from a few meters to hundreds of kilometers.
• Asteroids less than one meter in diameter are commonly referred to as meteorite impacts and micrometeoroids (grain-sized), with the precise distinction between the two categories long contested. 
• As of 2017, the IAU classifies asteroids ranging from 30 micrometers to 1 meter as micrometeoroids and smaller particles as “dust.” The asteroid belt orbits between Mars and Jupiter at a distance of 2.3 to 3.3 AU (340 to 490 million km; 210 to 310 million mi) from the sun.
• It is hypothesized to be relics of the Solar System’s creation that failed to merge due to Jupiter’s gravitational influence.
• The asteroid belt is home to tens of thousands, if not millions, of asteroids more extensive than one kilometer in diameter. Despite this, the overall mass of the asteroid belt is unlikely to be greater than a thousandth of that of Earth.
• The asteroid belt is sparsely inhabited; spaceships travel through it regularly without incident.

OUTER SOLAR SYSTEM

• The giant planets and their massive moons live in the Solar System’s outer zone, and it is also where centaurs and several short-period comets orbit.
• Since of their more considerable distance from the sun, solid objects in the outer Solar System have a more significant percentage of volatile components, such as water, ammonia, and methane, than those in the inner Solar System because lower temperatures enable these compounds to stay solid.

OUTER PLANETS

• The four outer planets, often known as giant planets or Jovian planets, account for 99% of the mass that circles the sun.
• Jupiter and Saturn are more than 400 times the mass of Earth and are mainly composed of the gases hydrogen and helium, therefore their nickname as gas giants.
• Uranus and Neptune are significantly less massive—each fewer than 20 Earth masses (MEarth)—and are mostly made up of ices. For these reasons, some astronomers believe they should be classified as ice giants.
• Although all four giant planets have rings, only Saturn’s ring system is visible from Earth. The phrase ideal world refers to planets outside Earth’s orbit, which encompasses the outer planets and Mars.

JUPITER

• It is mainly made up of hydrogen and helium. Jupiter’s intense internal heat produces semi-permanent atmospheric features like cloud bands and the Great Red Spot.
• The planet has a 4.2-14 Gauss magnetosphere that extends 22-29 million km, making it the most prominent object in the Solar System in specific ways.
• Jupiter has a total of 80 recognized satellites. The four biggest, Ganymede, Callisto, Io, and Europa, are known as the Galilean moons because they have features in common with terrestrial planets, such as volcanism and interior heating.

SATURN

• Saturn (9.5 AU (1.42 billion km; 880 million mi) from the sun) has numerous characteristics of Jupiter, including its atmospheric composition and magnetosphere.
• Saturn is the only planet in the Solar System with a density less than that of water. Saturn’s rings are composed of tiny ice and rocky particles.

URANUS

• It is the only planet that circles the sun on its sides; its axial tilt is more than 90 degrees to the ecliptic.
• Because each pole faces toward and away from the sun, the planet experiences significant seasonal change, and its core is substantially more relaxed than the other major planets. It emits relatively little heat into space.

NEPTUNE

• Neptune, albeit somewhat smaller than Uranus (30.1 AU (4.50 billion km; 2.80 billion mi) from the sun, is more massive (17 MEarth) and hence denser.
• It emits more internal temperature than Uranus but less than Jupiter or Saturn. Neptune is known to have 14 satellites.
• Neptune’s orbit is accompanied by several minor planets known as Neptune trojans, which either lead or tail the world by roughly one-sixth of the way around the sun at places known as Lagrange points.

KUIPER BELT

• The Kuiper belt is a gigantic ring of debris similar to the asteroid belt, except it is mainly made up of ice-based objects. It is 30 to 50 AU (4.5 to 7.5 billion kilometers; 2.8 to 4.6 billion mi) from the sun.
• It is mainly made up of tiny solar system bodies, while the giant handful is likely to be dwarf planets.

PLUTO AND CHARON

• Pluto is the most extensively known body in the Kuiper belt, with a typical orbit of 39 AU (5.8 billion kilometers; 3.6 billion mi) from the sun. It was thought to be the ninth planet when found in 1930; this changed in 2006 with the introduction of a formal definition of a planet.
• Pluto and Neptune have a 2:3 resonance, which means Pluto circles the sun twice for every three Neptunian orbits.
• Charon, Pluto’s most giant moon, is sometimes regarded as part of a binary system with Pluto, as the two worlds circle a gravitational barycenter above their surfaces (i.e., they appear to “orbit each other”). Pluto is orbited by four considerably smaller moons: Styx, Nix, Kerberos, and Hydra.

Solar System Worksheets

This is a fantastic bundle which includes everything you need to know about Solar System across 24 in-depth pages. These are ready-to-use Solar System worksheets that are perfect for teaching students about Solar System, which includes the Sun and all that orbit around it including planets, moons, comets, asteroids, gas, and dust. Scientists theorized that it was formed approximately 4.6 billion years ago after the collapse of a giant molecular cloud.

Complete List Of Included Worksheets

• Solar System Facts
• Naming Planets
• Relationship Goals
• Planet World
• Etymology
• Space Exploration
• Famous Astronomers
• Other Objects
• Truth About Earth
• Space Movies
• Mission to Mars

Frequently Asked Questions

Where did the Solar system word derive?

The term solar comes from the Latin word sol, which means “about the sun.”

How do planets and other objects orbits in our solar system?

Planets and most other objects circle the sun in the same direction as the sun rotates as a byproduct of the solar system’s development. That is, clockwise as seen from above the Earth’s north pole.

When did the Solar System begin?

The Solar System began from the gravitational collapse of an area within a massive molecular cloud 4.6 billion years ago. This first cloud was likely light-years broad and gave birth to multiple stars.

What includes in Inner Solar System?

The inner Solar System includes the rocky planets and the asteroid belt. The objects of the internal solar system, primarily silicates and metals, are pretty near the sun; the radius of this entire region is smaller than the distance between Jupiter and Saturn’s orbits.

Why do objects in the outer solar system have a more significant percentage of volatile components than those in the inner solar system?

Since of their more considerable distance from the sun, solid objects in the outer Solar System have a more significant percentage of volatile components, such as water, ammonia, and methane, than those in the inner Solar System because lower temperatures enable these compounds to stay solid.

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