History Channel's The Universe: How the Solar System Was Made Video Worksheet

4.6 billion years ago, a cold molecular cloud in the Milky Way Galaxy started to collapse. Over the next 700 million years, all of the crucial events that formed our solar system took place. Evidence for the solar system’s formation is seen today in the planets and earth itself and in other newly forming solar systems as seen through instruments such as the Hubble Space Telescope. Today we know that thousands of other solar systems exist, and we are beginning to be able to compare our planets to others in order to determine how common or uncommon we may be.

The worksheet consists of 35 multiple choice questions that follow the video, and a key is included. The download features MS Word and PDF versions of the video questions. You will need to obtain a DVD of the video or locate an internet site for streaming.

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Overview: History Channel’s The Universe: How the Solar System Was Made

The story of the solar system is ultimately the story of life on earth. 4.6 billion years ago, a shockwave from a nearby exploding star, a supernova, moved through a cold molecular cloud triggering its gravitational collapse into a rotating cloud of gas and dust. In the center was a protostar, our sun before becoming a full-fledged star. Today, the sun represents 99.85% of the solar system’s mass, and earth and the other planets are almost an afterthought. The early solar system developed specific regions related to proximity to the infant sun. Near the sun, all gas and dust was driven away by our star’s solar wind. Farther out, the inner solar system could support only rock and metal, a region known as the rock line. Much farther out, cold temperatures allowed water, methane, and ammonia to freeze. The edge of this region is termed the snow line. This early division is reflected in the characteristics of the planets. The inner planets, Mercury, Venus, Earth, and Mars are mostly rock and metal. The outer planets, Jupiter, Saturn, Uranus, and Neptune are mostly gas.

Collisions of matter in the early solar system led to the growth of “planetesimals”, small bodies only a mile or two in diameter. Bigger “planet embryos” eventually accreted forming “protoplanets”. Today, we see examples of these early objects in the asteroid belt between Mars and Jupiter. Jupiter itself began as a “super-earth” of about 10-15 earth masses. Jupiter began to devour abundant hydrogen gas to eventually become the large planet it is today, and the other outer planets, Saturn, Uranus, and Neptune grew in a similar manner. Today, Jupiter and Saturn contain 92% of the non-solar mass in the solar system. The accretion of such worlds can be seen today in other solar systems studied by the Suburu Telescope and the Hubble Space Telescope. Images show regions depleted of gas due to being absorbed by Jupiter-like planets.

At 50 million years of age, our sun became a star when nuclear fusion, the compression of hydrogen into helium, began in the protostar’s core. Nuclear fusion is the same energy released by a hydrogen bomb. Given its mass, the sun will fuse hydrogen for ten billion years, which has been long enough to support the emergence and evolution of life on earth.

The early solar system was a turbulent and chaotic place. Jupiter’s gravity “stirs up” the asteroid belt and prevented a single large planet from forming. Earth formed with a companion world named Theia which eventually struck the earth in at titanic impact creating the moon from the resulting debris. The larger outer planets didn’t have stable orbits, and at one time they were closer to the sun than today. Countless interactions with planetesimals caused the orbits to move over time due to the slingshot effect. Neptune had originally been positioned within the orbit of Uranus for example. The outer planets also boosted asteroids and icy objects in a region named the Kuiper Belt into different orbits or out of the solar system entirely. A resonance developed between Jupiter and Saturn which further exacerbated this cleaning out phase of the solar system. In a phase called the late heavy bombardment, objects flung from the asteroid belt hit the inner planets, and impact craters can be seen from this on the moon today. Planetesimal impacts with earth didn’t have all negative results. It is thought that most of earth’s water had been delivered by such impacts, and water is a necessary ingredient for life. Meteorites found on earth provide important information about the early solar system. One meteorite, Allende which fell in Mexico in 1969, contains some of the oldest known material. White inclusions in the meteorite date back 4.6 billion years and are thought to represent some of the first matter that accreted in the early solar system. The large asteroids Vesta and Ceres have been visited by NASA’s Dawn spacecraft. These worlds have survived from the early solar system in a pristine state due to the lack of weather or geologic forces such as earth has. NASA’s Juno mission has visited Jupiter with the goal of assessing whether Jupiter has a solid core and had formed as rapidly as theories suggest.

Today, we see molecular clouds in the constellation Orion, and the Hubble Space Telescope has revealed infant solar systems there still inside cradles of gas and dust. We have also been able to compare our solar system to others that have been discovered. These planets, termed exoplanets, orbit stars other than our sun. The Kepler Space Telescope has discovered thousands of these new planets. In comparison, our solar system may be an outlier or “oddball” in that we have such stable and regular orbits.