Science : TCAP

1. Science : TCAP By: Mary Mack Bell

2. Star Chart • A star chart is a map of the night sky that is divided into sections so that it can be used to locate and identify star patterns. • For centuries humans have studied the stars visible in the night sky. Today, even more stars are being discovered using high-powered telescopes, which make faraway objects look closer and brighter. • Astronomers organize stars into star charts so that they can locate and identify star patterns and track the apparent movement of stars in the night sky. In many cases, stars form patterns that look like familiar objects (animals, people, etc.). These patterns define specific areas of the sky called constellations. • Star charts are different in the Northern Hemisphere than in the Southern Hemisphere. This is because different stars are visible in each hemisphere. A star chart of the Northern Hemisphere is shown below.

3. STARS • Stars begin to shine in the sky as soon as the Sun sets. Actually, the stars are also out during the day, but the Sun is so bright that we cannot see them. • CONSTELLATIONS • Constellations are stars clustered together into recognizable groups. The stars in their constellations appear to travel together across the sky from east to west each night. However, it is the Earth's rotation on its axis that causes the stars to appear to move in this way. • This "apparent motion" is similar to the motion of the Sun and the Moon, which seem to people on Earth to "rise" in the east and "set" in the west each day. • SEASONS • If you look at the night sky at the same time of night, but at different times of the year, you will see different constellations. This happens because the Earth not only rotates on its axis, but it also orbits the Sun. • So, along with Earth's seasons which change throughout the year, there are "seasons" of the stars visible from Earth! • Each day, a few stars are visible in the east that could not be seen the night before. Likewise, a few stars in the west that were visible last night, are no longer visible tonight. The gradual changing of constellations in the night sky is due to the motion of the Earth around the sun. • NORTHERN AND SOUTHERN HEMISPHERES • School children in Australia (which is in the southern hemisphere) will see different stars from those seen by school children in the United States (which is in the northern hemisphere). This is because they are on opposite sides of the Earth. Stars visible to children in the northern hemisphere are not visible to those in the southern hemisphere because the Earth "blocks" their view.

4. PLANETS • If you look at the night sky regularly during a year, you will notice small disks that change in brightness and position against the background of other stars. The Greeks called these wandering stars planets. We know that there are 8 official planets in our solar system (shown below): The inner planets (Mercury, Venus, Earth, Mars) and the outer planets (Jupiter, Saturn, Uranus, Neptune). The inner planets each orbit the Sun in less than 2 years, but the outer planets take from 12 to 164 years each to orbit the Sun.

5. Inner Planets

6. Outer Planets • The outer planets (also known as the gas giants) are extremely large, cold, and made of gas (hydrogen, helium). Their orbits are farther out and spaced widely apart. • Jupiter is the largest planet (over 1,000 times the size of Earth) with colorful cloud bands and a large storm (The Great Red Spot). • Saturn has three large sets of rings surrounding it, which are visible in small backyard telescopes. Both Jupiter and Saturn have many moons (also called satellites) and are like mini-solar systems. Some of these moons could support life. • Uranus has smaller thin rings, has 21 moons, and is tipped on its side. • Neptune has eight .

7. MOONS • The moons in our solar system differ greatly in size. The largest of the moons in our solar system is Ganymede which orbits Jupiter. The second largest is Titan which orbits Saturn. Both of these moons are actually larger in size than Mercury, which is the smallest planet in our solar system. • The moons in our solar system also differ greatly in their composition. The most volcanically active body in our solar system is Io, a moon orbiting Jupiter. Another of the moons orbiting Jupiter, named Europa, is the most likely place in our solar system to find liquid water and possible life. It is believed that below the icy surface, there is a huge ocean of liquid water. • Only two of the planets in our solar system, Mercury and Venus, do not have any moons. Earth only has one moon, and all other planets have more than one moon. Jupiter and Saturn are orbited by more than 60 moons each

8. Comparing Star and Planets • Stars and planets can both be seen in the night sky. The planets that can be seen look a lot like stars in the night sky, but there are some differences between the way stars appear and the way planets appear. The best way to tell the difference between a planet and a star in the night sky is by their motion. The planets appear to move relative to the stars behind them. While A star's position compared to other stars does not change from one night to the next, a planet's position will. This is because the planets orbit the Sun while the stars do not. Also, the planets can appear to move East to West, West to East, or stand still. • There are a total of 5 planets that can be seen in the night sky with the unaided eye. They look like very bright stars and actually outshine the majority of the stars. Venus is the second brightest object in the night sky next to the Moon. • The biggest and most obvious difference between the planets and stars is that while stars produce their own light, the light seen from planets is only reflected light from the Sun.

9. Did you now….. • The greater the star's mass, the shorter its lifecycle. • The spiral galaxy closest to our Milky Way galaxy is Andromeda. Andromeda is over 2 million light-years away. Its central bulge and spiral arms are tilted toward us at a 15 degree angle. • The gravitational pull of a black hole is so powerful that even light cannot escape from it.

10. science(universe)

11. The end!!!