Universe Cycle - Universe (2)
Pre Lab 

  • Discovering stars.
  • Identifying and comparing constellations.
  • constellation
  • galaxy
  • light year
  • nebula
  • star
  • universe

Students identify Orion and Ursa Major.


The Universe is a vast space of unknown dimensions. The Milky Way is our address in the Universe. Our Sun is only one small component amongst the other billions of stars in our galaxy, the Milky Way. The Solar System is a group of 9 planets that revolve around the Sun.

We see objects in the night sky because they are either generating or reflecting light. While these objects also shine or reflect light during the day, we generally cannot see them because they are much dimmer than the bright light emitted by the nearby Sun.

Most of the light we see at night comes from within our own galaxy, the Milky Way. Some points of light, however, are from other galaxies or nebulas, which are glowing clouds of gas within our galaxy.

Most of the stars and galaxies we see at night are very far away. This is difficult for humans to comprehend. We do not even measure the distance in kilometers; instead, we use light years. Light travels about 300,000 km per second, faster than anything we know. A light year is the distance light can travel in one year, an almost unimaginable number. Multiply the number of seconds in one year (31,557,000) times 300,000 km/yr. This results in a distance of 9,467,100,000,000 km per year, or about 9.5 quadrillion kilometers/year.

When ancient people looked in the night sky, they noticed groups of stars which formed images of animals, gods, and heroes. In the silence and darkness, ancient humans started to tell stories to one another for entertainment. The students will look at two constellations in the lab: Orion and the Big Dipper.

Orion was a hunter who was killed by a giant scorpion. He was placed in the sky but was still chased by the scorpion, which is found in a constellation (Scorpio) on the other side of the sky. When Orion is visible, the scorpion is below the horizon. When the scorpion rises, Orion sets, so that they are never visible at the same time. The Big Dipper is actually part of the Ursa Major (Big Bear) constellation, and represents a cup with a long handle.

These points of light in the sky, and the shapes they represented, were also important for traveling at night and for determining the time of the year. The constellations, as they are now called, helped to guide the early people in many ways.

The constellations are groupings of points of light, as seen from the Earth. Some of the points of light may represent far away galaxies, but the majority represent individual stars. There are 88 constellations that have been part of a historical written record. There are many other cultures who had terms for patterns of light, but unfortunately their record was not passed on through generations like the European/North African stories. These constellations will help students orient themselves in the nighttime sky.

  1. Show students a celestial globe or a picture of the night sky. In the celestial globe the Earth is in the center. Tell students that if they are standing on the Earth and looking up they will see the stars on the other clear globe. If you are standing in the United States the stars you see in the sky are different than if you are standing on Australia. There is many directions to the Universe, depending on where you are looking.
  2. Tell the students that we cannot see all the points of light of the night sky that are shown in many books (as shown the Glow in the Dark Night Sky Book) because of city lights and haze. Ask the students to name things that they may see in the night sky (moon, stars, satellites, planets, and galaxies). Explain that only stars and galaxies shine, or emit light; the other sky objects all reflect light.
  3. You may want to ask students, how fast does light travel? They may never have thought about this question before. Switch the light on and off and ask them how long it takes the light to move from the bulb to the ground. Students won't be able to time such an event. Explain the speed of light and light years. You may want to compare the speed of light with the speed of a car on the freeway which is about 80 km per hour or 1.33 km per minute or .02 km per second. Light is fast!
  4. Ask the students which objects make their own light. Stars generate light because they are giving off energy. Ask them which star is closest to us. If they do not know, explain that it is our own Sun. Tell them that stars are like our Sun, but very far away. Show pictures of different types of stars, and say that our Sun is only a medium size star.
  5. Explain that patterns of stars are called constellations, and that there are stories about some of these groups. Astronomers now use 88 constellations to help divide the Universe into areas. Scientists use these to help locate components in that sector. So the term constellations can mean a historical grouping of stars with stories and myths associated with them, or as a way to locate an area on a Celestial Globe.
  6. Have the students read, "The Big Dipper."

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