Week 4: Our Solar System

Formative Assessment: Stars

Planets

There are 8 planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. To remember the order of the planets (closest to farthest from the sun), use the acronym “My Very Educated Mother Just Served Us Nutella.”

The four inner planets–Mercury, Venus, Earth, and Mars–are rocky planets because they have a solid surface. The four outer planets–Jupiter, Saturn, Uranus, and Neptune–are gaseous planets because they are composed of gases, mainly hydrogen and helium. Notice that the rocky planets are much smaller in size and the gaseous planets are larger. One theory for this is that when the Sun turned on and became a star, it caused the gas clouds of the four inner planets to blow away. The rocky planets were left with a smaller, solid planet. The gaseous planets are farther from the sun, so they retained their composition. As they increased in mass, their gravity increased which allowed them to attract more and more material from space and grow larger in size.

Sizes and Distances of Planets

The image below shows the huge variance in size between planets in our solar system. Notice the differences in size between the inner, rocky planets and the outer, gaseous planets.

Watch the following video to see a size comparison of the planets across Iowa’s campus.

To understand the scale of the Hubble eXtreme Deep Field, watch the video below:

Video credit: “How Small are We in the Scale of the Universe?” by Alex Hofeldt/TED-Ed  is licensed under CC BY-NC-ND 4.0

Why is Pluto Not a Planet?

Pluto was the ninth planet in our solar system until a controversial 2006 decision when it was reclassified as a dwarf planet. Pluto meets two requirements to be a planet: it orbits around the sun and its gravity formed the planet into a round shape. However, it does not meet the third requirement of “clearing the neighborhood.” Planets must have gravitational dominance and clear the neighborhood around their orbit; this means that large planets (more mass=more gravity) either attract or eject other, smaller bodies from that region of space. Several other dwarf planets and similarly-sized space objects were discovered in the solar system near Pluto’s orbit in the Kuiper Belt. Therefore, Pluto has not cleared the neighborhood and so it cannot be considered a planet.

The Big Bang: Origins of our Universe

The Big Bang is the best-supported scientific theory for how the universe was created. 13.7 billion years ago there was nothing and nowhere. Everything that ever existed was contained in a subatomic particle that was billions of times smaller than an atom. Within a fraction of a second, this amazingly tiny particle stretched and inflated to an unimaginably huge size. Space, time, and the fundamental particles of the universe were created in this instant.

Although there are alternate theories, the Big Bang theory is supported by multiple sources of scientific evidence.

1. Edwin Hubble discovered that the universe is still expanding today. If it is constantly expanding and growing now, that means it was smaller before–and likely the size of an unimaginably small particle at the beginning.
2. Scientists detected Cosmic Microwave Background, a type of radiation that is present everywhere in the universe. Evidence suggests that this is leftover radiation from the energy of the Big Bang.

For more explanation of the Big Bang theory, watch the following video.

Video credit: “Big Bang Introduction” by Khan Academy is licensed under CC BY-NC-SA 3.0. Note: All Khan Academy content is available for free at khanacademy.org.

Origins of the Sun, Earth, and Moon

Our solar system was most likely formed from a giant rotating nebula after a former star underwent a supernova. 4.65 billion years ago, this rotation and intense gravity caused the nebula to collapse on itself. This caused it to spin faster and flatten into a disk shape, the Plane of the Ecliptic. Much of this material was pulled toward the center of the disk and a star was formed: the Sun. The Sun contains 99.8% of the mass in our solar system.

Although it is enormous compared to the size of Earth, the Sun is an average-sized star. It is mostly made of hydrogen and helium. Currently, it is halfway through its fuel supply. In around 5-6 billion years, the Sun will burn all of its fuel and become a white dwarf star.

After the Plane of the Ecliptic was formed, the planets formed from the leftover gas and dust orbiting around the Sun. One theory says that when the Sun turned on and became a star, the force of its energy blew off the gas clouds around the four inner planets which is why they are rocky and the outer planets are gaseous. Earth, a rocky planet, is about 4.65 billion years old. Scientists believe that life on Earth appeared approximately 3.5 billion years ago, based on evidence found in fossils.

For more detail of how space dust turns into planets, watch the video below:

Video credit: “The Dust Bunnies That Build Our Planet” by Lorin Swint Matthews/TED-Ed  is licensed under CC BY-NC-ND 4.0

NGSS:

ESS1.A: The Universe and its Stars

• Patterns of the motion of the sun, moon, and stars in the sky can be observed, described, and predicted. (1-ESS1-1)

Fifth Grade

ESS1.B: Earth and the Solar System

• The orbits of Earth around the sun and of the moon around Earth, together with the rotation of Earth about an axis between its North and South poles, cause observable patterns. These include day and night; daily changes in the length and direction of shadows; and different positions of the sun, moon, and stars at different times of the day, month, and year. (5-ESS1-2)

Middle School

ESS1.A: The Universe and Its Stars

• Patterns of the apparent motion of the sun, the moon, and stars in the sky can be observed, described, predicted, and explained with models. (MS-ESS1-1)

ESS1.B: Earth and the Solar System

• The solar system consists of the sun and a collection of objects, including planets, their moons, and asteroids that are held in orbit around the sun by its gravitational pull on them. (MS-ESS1-2),(MS-ESS1-3)
• This model of the solar system can explain eclipses of the sun and the moon. Earth’s spin axis is fixed in direction over the short-term but tilted relative to its orbit around the sun. The seasons are a result of that tilt and are caused by the differential intensity of sunlight on different areas of Earth across the year. (MS-ESS1-1)

Crosscutting Concepts

Patterns

• Patterns in the natural world can be observed, used to describe phenomena, and used as evidence. (1-ESS1-1),(1-ESS1-2)

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

            Connections to Nature of Science

Scientific Knowledge Assumes an Order and Consistency in Natural Systems

• Science assumes natural events happen today as they happened in the past. (1-ESS1-1)
• Many events are repeated. (1-ESS1-1)

Lesson ideas:

Take children outside to see the Moon in the daytime. Show them how to observe the Moon, and keep a Moon journal, and encoruage them to look for the Moon day and night. Look at your Moon journal to see what the patterns are.

Try to recreate what they see outside with the Earth Sun Moon system.

Performance Expectations

DCI

5th Grade

PS2.B: Types of Interactions

• The gravitational force of Earth acting on an object near Earth’s surface pulls that object toward the planet’s center. (5- PS2-1)

ESS1.A: The Universe and its Stars

• The sun is a star that appears larger and brighter than other stars because it is closer. Stars range greatly in their distance from Earth. (5-ESS1-1)

middle School

ESS1.B: Earth and the Solar System

• The solar system consists of the sun and a collection of objects, including planets, their moons, and asteroids that are held in orbit around the sun by its gravitational pull on them. (MS-ESS1-2),(MS-ESS1-3)

• The solar system appears to have formed from a disk of dust and gas, drawn together by gravity. (MS-ESS1-2)

Crosscutting Concepts

Patterns

• Similarities and differences in patterns can be used to sort, classify, communicate and analyze simple rates of change for natural phenomena. (5-ESS1-2)

Cause and Effect

• Cause and effect relationships are routinely identified and used to explain change. (5-PS2-1)

Scale, Proportion, and Quantity

• Natural objects exist from the very small to the immensely large. (5-ESS1-1)

Patterns

• Patterns can be used to identify cause-and-effect relationships. (MS-ESS1-1)

Scale, Proportion, and Quantity

• Time, space, and energy phenomena can be observed at various scales using models to study systems that are too large or too small. (MS-ESS1-3)

Systems and System Models

• Models can be used to represent systems and their interactions. (MS-ESS1-2)