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Module 15 Planets
Secondary education (bio sci)
Eastern Visayas State University
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Module 15
Planets in the Solar System
What this module is about
Have you ever wondered what lies beyond earth? Try to look at the sky at night. What are the things that you see? You probably have seen the moon and the stars. Some bright objects in the sky are the other planets. Sometimes we see meteors and comets. Would you like to learn more about them? Come, let us explore the Solar system.
This module will help you find out many things about our solar system. There will be activities prepared for you to help you understand our lesson much better. Self-tests are also provided for you for a good look at your progress. Have fun and enjoy learning the following lessons:
Lesson 1 - The Origin of the Solar System Lesson 2 - Sun: The Center of the Solar System Lesson 3 - Our Neighbors: A Close Look
What you are expected to learn
- Describe how the solar system evolved.
- Describe how the sun emits its energy.
- Identify the members of the solar system.
- Compare the physical properties of the planets.
- Identify the newest member of the solar system.
How to learn from this module
Here’s a simple guide for you in going about the module.
- Read and follow the instructions very carefully.
- A simple 10-item multiple-choice test is provided at the start of this module to determine how much you know about the module.
Key to answers on page 26
Of all the planets in the solar system, which is the closest to the Earth in terms of size and mass. a. Mars b. Mercury c. Venus d. Pluto
Which of the following statements is correct? a. Pluto is the smallest planet – it is smaller than the Earth’s moon. b. Mars is the smallest planet – it is smaller than the Earth’s moon. c. Venus is the smallest planet – it is smaller than the Earth’s moon.
When is energy in the Sun produced? a. During the conversion of hydrogen atoms into helium atoms. b. During the conversion of helium atoms into hydrogen atoms.
Which of the following statements is correct? a. Saturn's moon, Titan, is the largest moon in the solar system. b. Jupiter's moon, Ganymede, is the largest moon in the solar system. c. Neptune's moon, Triton, is the largest moon in the solar system.
Which statement is true? a. Mercury is the hottest planet and Pluto is the coldest planet. b. Venus is the hottest planet and Pluto is the coldest planet. c. Mercury is the hottest planet and Neptune is the coldest planet.
Pick the true statement: a. The Sun consists mostly of hydrogen. b. The Sun consists mostly of helium. c. Sunspots appear all over the Sun, not just in one small area.
Key to answers on page 26
Lesson 1 The Origin of the Solar System
. What you will do
Activity 1 Theories about the Solar System
Try this! Match the scientist to the theory and view attributed to him. Draw a line, which will connect one to the other.
Origin of the Solar System
There were two different views about our solar system. Ptolemy, a famous astronomer, once said that earth is the center of the solar system and everything moves around it. This idea is known as the geocentric view of the solar system. Geo means earth and centric means center. His idea was anchored on the fact that man is known to be created like God thus he must be very close to God.
Coppernicus, on the other hand, is one great man who opposed Ptolemy’s theory. He said that the sun is the center of the solar system and revolving around it are the planets. This is known as the heliocentric theory (helio –fire and centric – center). Now who do you think has a better idea?
What you will do
Activity 1 The Origin of the Solar System
Read this!
Did you know how the solar system was formed?
The orderly nature of our solar system is believed by astronomers to have formed 5 billion years ago. The planets, the sun and all other members of the solar system are
Sun – Centered Solar system
Earth – Centered Solar system
Heliocentric Theory
Geocentric Theory
Copernicus
Ptolemy
Key to answers on page 26
turn around. Your motion around the chair is like the motion of all the planets around the sun. This is called revolution. One complete revolution of a planet means one complete year of the planet. On the other hand, when you turn around in one place, the motion is basically called rotation. All planets in the solar system rotate about their own axis (axis - an imaginary line running across the planet on which the planet turns about). One complete rotation is equivalent to one whole day in the planet.
What you will do
Activity 1 Orbits
Oops! Before you go on, try this one!
What you will do
Self-Test 1.
Here’s a good glimpse of the motion of each planet.
Name Time for 1 revolution (in Earth time)
Time for 1 rotation (in Earth time) Mercury 88 days 179 days Venus 225 days 244 days Earth 1 year 23h 56m 04s Mars 1 years 24h 37m 23s Jupiter 12 years 9h 50m Saturn 29 years 10h 14m Uranus 84 years 17h 14m Neptune 165 years 16h 03m Pluto 248 years 6 days
Identify the planet located on the orbits based on the time for 1 revolution
2.
3
4
5
1
Key to answers on page 27
Direction: Choose the letter of the best answer. Write the chosen letter on a separate sheet of paper.
Which term means Earth –centered? a. Heliocentric b. Geocentric
Which of the following statement is TRUE? a. The Sun is at the center of a heliocentric system. b. The Moon is at the center of a heliocentric system. c. The Earth is at the center of a heliocentric system.
Which of the two statement is TRUE? a. Geocentric means Sun-centered, heliocentric means Earth-centered. b. Geocentric means Earth-centered, heliocentric means Sun-centered.
Scientists hypothesize that the Sun formed ____. a. less than a billion years ago b. from a cloud of gas and dust c. less than a million years ago d. from a chunk of Jupiter
People once believed that all planets and stars orbited around ____. a. Mercury b. Venus c. Earth d. Mars
If you score 3 or more out of 5 – Congratulations!
You may now proceed to the next lesson. If you score below 3 you need to go back and read the lesson again!
like water vapor. Other organisms need sunlight for them to be able to maintain constant body temperature. Temperature is the hotness or coldness of a body. People like us need sunlight for our skin to produce vitamin D, which is essential to living. Other countries make use of sunlight as their main source of energy. They make use of solar cells or solar panels to collect sunlight and convert this energy to electrical energy that can light their houses, cook their food, and iron their clothes, and wash their clothes. What about you, how can you make use of sunlight?
Here’s a simple activity that can give you an idea how you can make use of solar energy for practical purposes
What you will do
Activity 2 Solar Power
Goal: You will investigate solar power.
Materials large bowl aluminum foil plastic knives or spreaders paper plates and napkins Peanut butter (refrigerated) cheese crackers stop watch
Procedure
Make a solar oven by lining the inside of a large bowl with aluminum foil. Place a glob of cold peanut butter on the bottom of the bowl, and position the bowl in direct sunlight so that the sun's rays are shining on the inside of the bowl. You may need to use blocks to prop the bowl at an angle to catch the rays.
Let the bowl sit for about an hour and regularly check the melting progress. Then spread the melted peanut butter on crackers and serve for a simple picnic treat.
Put a slice of cheese on one cracker and some stiff peanut butter on another. Predict which will melt first. Then find other items to melt, such as an ice cube, crayon, and candle. Record on a chart the time it takes each item to melt, and compare your predictions.
Data and Results
Material Predicted Melting Time Actual Melting Time Cheese Crayons Ice cube Birthday candle
Guide Questions:
- What can you tell me about the sun?
- How do people use it?
- How is an oven like the sun?
Oops! Before you go on, try this one!
What you will do
Self-Test 2.
Direction: Choose the letter of the best answer. Write the chosen letter on a separate sheet of paper.
- Compared to other stars, the sun is _______________. a. small b. medium-sized c. large
Key to answers on page 27
layers. The layer closest to the sun is the photosphere , which is about 550 kilometers thick. It is the layer that emits the sun’s light.
The chromosphere is the layer of the sun’s atmosphere next to the photosphere. It is believed to be responsible in emitting the color of the sun. The corona is the last layer of the sun’s atmosphere. It is also known as the crown of light that surrounds the sun. ( Corona comes from the Latin word meaning crown ). The corona is the layer of the sun’s atmosphere farthest from the sun. The temperature in the corona is more than 1 million degree Celsius.
What you will do
Self-Test 2.
Direction: Choose the letter of the best answer. Write the chosen letter on a separate sheet of paper.
The layer of the sun’s atmosphere next to the photosphere is the ____________. a. corona b. chromosphere c. solar sphere
The chromosphere can best be seen _______________. a. on a dark, moonless night b. during a solar eclipse c. at noontime on a sunny day
Which among the following is the layer of the sun’s atmosphere that is responsible for emitting white light? a. Photosphere b. Chromosphere c. Corona
Which layer of the sun’s atmosphere is farthest away from the sun? a. Photosphere b. Chromosphere c. Corona
When does the corona become visible? a. During solar eclipse b. During solar flare c. During prominence
Remember this!
Now let’s take a close look at the different planets of the solar system. The four planets closest to the sun are known as the inner planets. Often times they are also called terrestrial planets since all of them appear solid and they look like our very own planet – The Earth!
Mercury: The Innermost Planet
Mercury is the closest planet to the sun, thus, it is considered as the innermost planet. Like our moon, it absorbs most of the sunlight that strikes it and reflects only about 6% into space. This happens because Mercury has no atmosphere like our moon.
No moon accompanies Mercury. It revolves quickly ( days) but rotates slowly (179 days), thus, a night on Mercury lasts for about 3 months followed by 3 months of daylight. Mercury is also known as a very cold planet at nighttime with a temperature of about – 173oC. However it becomes very hot at daytime with a temperature of about 427oC, hot enough to melt tin and lead! You
Here’s an easier way of remembering the planets starting from the one closest to the sun!
M y V ery E ager M other J ust S erved U s N ine P utos: The
Planets of the Solar System (Mercury, Venus, Earth, Mars,
Jupiter, Saturn, Uranus, Neptune, Pluto)
Mercury Venus Mars Earth
Figure 3. The Terrestrial Planets
Figure 3. Mercury
could probably have 3rd degree burns or worse if you go there without life support. Consequently, no life has ever been discovered in Mercury.
Venus: The Goddess of Love and Beauty!
Venus is the brightest planet in the night sky next to our moon. It is usually called the twin planet of Earth because it shares a lot of similarities with Earth in terms of size, density, mass and location in the solar system. It orbits the sun in 2 25 days. The Venusian surface reaches temperature of about 475 oC. This is because its thick atmosphere prevents excess sunlight to escape the planet. Its very thick atmosphere is composed mostly of carbon dioxide (97%). This environment makes it impossible for life to exist on Venus.
Mars: The Red Planet
Mars is believed to be the home of John Jones of Justice League and Marvin the Martian of Looney Toons. Oopps! Just kidding!
Through a telescope, Mars appears as a reddish ball with some dark regions. We can also see polar ice caps which look like those we have on Earth. The Martian atmosphere has only 1% the density of earth’s atmosphere. It is primarily composed of carbon dioxide with tiny amounts of water vapor. Data from discoveries confirm that polar ice caps on Mars are made of water ice, covered by thin layer of frozen carbon dioxide. When the dust that covers Mars during sandstorm clears, images of the northern hemisphere show numerous large volcanoes. The biggest of which is the Mons Olympus.
Did you also know that Mars has moons or natural satellites? They are named as Phobos and Deimos. It is believed that these moons are asteroids captured by Mars!
Figure 3. Venus
Figure 3 Mars
Saturn: The Ringed Planet
Saturn is known to be the most elegant planet in the solar system because of its rings which are very visible to the eyes. It circles the sun in about 29 Earth years. Thus, one complete year in Saturn is about 29 years on earth. Saturn’s rings were first seen by Galileo in 1610. Recent discoveries confirm that these rings are made up of ice rocks. At present, Saturn has about 21 natural satellites, the most prominent of which is known as Titan.
The Twins: Uranus and Neptune
Uranus is known as the sideways planet because the planet rotates “on its side”. Its axis of rotation is parallel to its orbit. Uranus is the seventh planet from the Sun and is the third largest in the solar system. It was discovered by William Herschel in 1781. It has an equatorial diameter of 51800 kilometers ( miles) and orbits the Sun once every 84. Earth years. It has a mean distance from the Sun of 2 billion kilometers (1 billion miles). The length of a day on Uranus is 17 hours 14 minutes. Uranus has at least 22 moons. The two largest moons, Titania and Oberon, were discovered by William Herschel in 1787.
Neptune is the outermost planet of the gas giants. It has an equatorial diameter of 49500 kilometers (30760 miles). If Neptune were hollow, it could contain nearly 60 Earths. Neptune orbits the Sun every 165 years. It has eight moons, six of which were found by Voyager. A day on Neptune is 16 hours and 6 minutes. Neptune was discovered on September 23, 1846 by Johann Gottfried Galle, of the Berlin Observatory, and Louis d'Arrest, an astronomy student, through mathematical predictions made by Urbain Jean Joseph Le Verrier.
The first two thirds of Neptune is composed of a mixture of molten rock, water, liquid ammonia and methane. The outer third is a mixture of heated gases comprised of hydrogen, helium, water and methane. Methane gives Neptune its blue cloud color. Neptune has a set of four rings, which are narrow and very faint. The rings are made up of dust particles thought to have been made by tiny meteorites smashing into Neptune's moons.
Uranus Neptune
Figure 3 Saturn
Module 15 Planets
Course: Secondary education (bio sci)
University: Eastern Visayas State University
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