Name: __________________________________ Date: ____________________ Period: ___ GALAXIES STEP 1 Read the article below. Galaxies are collections of billions of stars, planets, dust, and gas held together by gravitational attraction. Until the 1920’s, the prevailing scientific view was that the entire universe was found within the Milky Way. However, American astronomer Edwin Hubble devised a new method to calculate the distance of celestial objects using stars called Cepheid variables. Using a brand-new telescope at the Mount Wilson Observatory in California, Hubble found that what appeared to be nebulae (clouds of dust and gas) were actually gigantic galaxies outside of the Milky Way. Hubble classified galaxies by their structure and created an identification chart that resembled a tuning fork. He recognized that galaxies went through an evolution over time. While no two galaxies are exactly alike, there are four major types: spiral, barred spiral, elliptical, and irregular. Spiral galaxies are perhaps the most familiar. They have a circular, disk-like shape, a bulging center containing a supermassive black hole, and arms that spiral outwardly like bands of a hurricane. Barred spirals are spiral galaxies that have a unique bar-shaped region of stars in the center. Spiral galaxies are young, blueish, and have active star formation. The Milky Way is likely a barred spiral. Elliptical galaxies are older, reddish, and oval-shaped. They have used up most of their gasses and the formation of new stars is nearing an end. Our massive galactic neighbor, Andromeda, is one such example. Lastly, irregular galaxies have no defined structure. They can be galaxies in their early formation or the result of collisions between galaxies. Pinwheel Galaxy, Photo Courtesy of NASA STEP II Write in the missing word to complete the statements below. 1. ___________________ galaxies are younger, bluer, and have active star formation. 2. American astronomer ____________________________ discovered gigantic galaxies outside of the Milky Way. 3. Spiral galaxies have arms that spiral outwardly like the bands of a ___________________________. 4. Our galaxy, the ________________________, is likely a NOW: Complete the statements to the right. STEP III Find and circle your answers on the grid below. Note: Words can read in any direction. barred spiral. 5. ________________________ galaxies have no defined structure. 6. Galaxies that are older, oval-shaped, and reddish are _________________________. 7. At the center of many galaxies is a supermassive ________________________. 8. Irregular galaxies are in their early formation or are the result of _______________________ between galaxies. 9. Galaxies go through an ___________________ over time. 10. _______________________ are clouds of dust and gas. 11. Galaxies are held together by ______________________ attraction. 12. _____________________________ is an elliptical galaxy. 13. Hubble used ____________________________ stars to STEP IV Now read left to right, row by row, the first 38 letters you have not circled for a hidden message about galaxies. Write it here: ________________________________________________ help determine the distances of celestial objects. 14. Hubble performed his observations at the Mount Wilson Observatory in ___________________________. Name: __________________________________ Date: ____________________ Period: ___ GALAXIES- KEY STEP 1 Read the article below. Galaxies are collections of billions of stars, planets, dust, and gas held together by gravitational attraction. Until the 1920’s, the prevailing scientific view was that the entire universe was found within the Milky Way. However, American astronomer Edwin Hubble devised a new method to calculate the distance of celestial objects using stars called Cepheid variables. Using a brand-new telescope at the Mount Wilson Observatory in California, Hubble found that what appeared to be nebulae (clouds of dust and gas) were actually gigantic galaxies outside of the Milky Way. Hubble classified galaxies by their structure and created an identification chart that resembled a tuning fork. He recognized that galaxies went through an evolution over time. While no two galaxies are exactly alike, there are four major types: spiral, barred spiral, elliptical, and irregular. Spiral galaxies are perhaps the most familiar. They have a circular, disk-like shape, a bulging center containing a supermassive black hole, and arms that spiral outwardly like bands of a hurricane. Barred spirals are spiral galaxies that have a unique bar-shaped region of stars in the center. Spiral galaxies are young, blueish, and have active star formation. The Milky Way is likely a barred spiral. Elliptical galaxies are older, reddish, and oval-shaped. They have used up most of their gasses and the formation of new stars is coming to its end. Our massive galactic neighbor, Andromeda, is one such example. Lastly, irregular galaxies have no defined structure. They can be galaxies in their early formation or the result of collisions between galaxies. Pinwheel Galaxy, Photo Courtesy of NASA STEP II Write in the missing word to complete the statements below. 1. _______Spiral________ galaxies are younger, bluer, and have active star formation. 2. American astronomer ________Edwin Hubble________ discovered gigantic galaxies outside of the Milky Way. 3. Spiral galaxies have arms that spiral outwardly like the bands of a _________hurricane____________. 4. Our galaxy, the ________Milky Way______, is likely a NOW: Complete the statements to the right. STEP III Find and circle your answers on the grid below. Note: Words can read in any direction. barred spiral. 5. ________Irregular__________ galaxies have no defined structure. 6. Galaxies that are older, oval-shaped, and reddish are _______elliptical____________. 7. At the center of many galaxies is a supermassive _________black hole___________. 8. Irregular galaxies are in their early formation or are the result of _________collisions________ between galaxies. 9. Galaxies go through an ____evolution______ over time. 10. _____Nebulae__________ are clouds of dust and gas. 11. Galaxies are held together by _____gravitational______ attraction. 12. _________Andromeda__________ is an elliptical galaxy. 13. Hubble used _______Cepheid variable_______ stars to STEP IV Now read left to right, row by row, the first 38 letters you have not circled for a hidden message about galaxies. Write it here: ___NASA’s space telescope was named after Hubble___ help determine the distances of celestial objects. 14. Hubble performed his observations at the Mount Wilson Observatory in ______California________.
