What Happened to the Galaxies Catalogue?

What happened to the Galaxies' Catalogue? Mysteriously, every catalogue for the galaxies have disappeared. At the same time, a cry for help has been heard by a Radio Telescope, saying that a fatal disease as struck every spiral galaxies on the far side of the Universe. They ask our help in transporting a newly found serum that will save the Universe. But you do not know which galaxies are spiral. You and your team have been assembled to recatalogue our galaxies, so that we may launch our newly developed Hyperdrive Ships and deliver this serum. HURRY. TIME IS RUNNING OUT!!!!

But what is a galaxy?

Write your groups answer in your notebook before turning the page.

The dictionary says that a Galaxy is a massive ensemble of hundreds of millions of stars, all gravitationally interacting, and orbiting about a common center. All the stars visible to the unaided eye from earth belong to the earth's galaxy, the Milky Way. The sun with its associated planets is just one star in this galaxy. Besides stars and planets, galaxies contain clusters of stars; atomic hydrogen gas; molecular hydrogen; complex molecules composed of hydrogen, nitrogen, carbon, and silicon, among others; and cosmic rays.

Centuries ago (about 950 AD), al-Sufi, a Persian astronomer, described a the spiral galaxy seen in the constellation Andromeda. By the middle of the 18th century, only three galaxies had been identified. In 1780, the French astronomer Charles Messier published a list that included 32 galaxies.

Thousands of galaxies were identified since 950 AD. The British astronomers Sir William and Caroline Herschel and Sir John Herschel, alone identified thousands of galaxies and other astral bodies during the early part of the 19th century. From 1786 to 1802, Sir Herschel cataloged 2500 galaxies. Since 1900 galaxies have been discovered in large numbers using photographic searches by professional and amateur astronomers the world over.

Who was the first to observe and name a galaxy?

How many galaxies have been identified and cataloged since 950 AD?

One piece of luck came to the CIA team investigating a High School library where the encyclopedia section that contained information about the galaxies disappeared. They found a torn page from the book that has the following information written on it.

. . . When viewed or photographed with a large telescope, only the nearest galaxies exhibit individual stars. For most galaxies, only the combined light of all the stars is detected. Galaxies exhibit a variety of forms. Some have an overall globular shape, with a bright nucleus. Such galaxies, called ellipticals, contain a population of old stars, usually with little apparent gas or dust, and few newly formed stars. Elliptical galaxies come in a vast range of sizes, from giant to dwarf. Elliptical galaxies are spherical or ellipsoidal systems; they contain no trace of spiral arms.

In contrast, spiral galaxies are flattened disk systems containing not only some old stars but also large populations of young stars, much gas and dust, and molecular clouds that are the birthplace of stars. Often the regions containing bright young stars and gas clouds are arranged in long spiral arms that can be observed to wind around the galaxy. Generally a halo of faint older stars surrounds the disk; a smaller nuclear bulge often exists, emitting two jets of energetic matter in opposite directions.

More than two-thirds of the thousand most conspicuous galaxies in the sky are spirals. Because of this, many people think that most galaxies are spiral. In truth, most galaxies are very hard to see, because they have relatively low luminosity (light).

Other dislike galaxies, with no overall spiral form, are classified as irregulars. These galaxies also have large amounts of gas, dust, and young stars, but no arrangement of a spiral form. They are usually located near larger galaxies, and their appearance is probably the result of a tidal encounter with the more massive galaxy. So the same tidal forces that make high and low tides on Earth's oceans also affect galaxies. Some extremely peculiar galaxies are located in close groups of two or three, and their tidal interactions have caused distortions of spiral arms, producing warped disks and long streamer tails. Irregular galaxies make-up about 3 percent of the brightest-appearing galaxies in the northern sky.

In your notebook, draw a spiral galaxy and an elliptical galaxy.

What is a tidal force? Do tidal forces affect galaxies?

More luck. Another team of Chilean police found a old file filled with thousands of pictures of galaxies. Your team have been sent 30 to sort out into the proper classification.

Also, ...

NASA ask for any addition help, such as how far the galaxies are, and what would be the quickest path from Earth to all of the Spiral Galaxies in the universe.

In your notebook, draw a picture of the solar system. Use your notes from the Midterm and presentations.

Draw what you think would be the best route out of our solar system. Write next to Earth and your path-line the earliest time that you can leave.

But time is running out. In 1912 the American astronomer Vesto M. Slipher, working at the Lowell Observatory in Arizona, discovered that the lines in the spectrum of all galaxies were shifted toward the red spectral region. This was interpreted by the American astronomer Edwin Hubble as evidence that all galaxies are moving away from one another and led to the conclusion that the universe is expanding. It is not known if the universe will continue to expand, but as of now, they are. So those who need the serum are getting farther away, as we catalogue the galaxies. HURRY!!!

Galaxies Lesson Plan
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