Science 9 Unit 5: Space Name:



Science 9 Unit 5: Space Name: Danielle Murray

Topic 7 – The Solar System Up Close

The Sun

The Sun is made up of mostly hydrogen gas. It is 1.4 million km in diameter. Its temperature is about 15 million degrees Celsius. 600t of hydrogen are converted, by nuclear fusion, into helium per second. This is the energy released from the Sun. The Sun emits charged particles in all directions. This solar wind bombards the Earth at 400km/s, but the magnetic field of the Earth protects us.

Traveling through The Solar System

The formation of our solar system is based on the ‘protoplanet hypothesis’, which follows three steps:

1. A Nebula or a cloud of gas & dust in space begins swirling

2. Most of the matter (more than 90% of it) accumulates in the

center – forming the Sun

3. The remaining materials accumulate (forming planets) and

circle the Sun

The only way to see the detail on the planets in our solar system was to send spacecraft up close to take pictures and send them back to the Earth.

The Moon - The first “other world” seen up close was the Moon. On July 17, 1969 Neil Armstrong and Edwin Aldrin landed on the moon for a first hand look.

The Planets-

• The Inner Planets (Terrestrial)- Mercury, Venus, Mars and the Earth - are considered the terrestrial planets because of their composition.

• The Outer Planets (Gas Giant) – Jupiter, Saturn, Uranus, Neptune, and Pluto – are similar because of their gaseous composition.

Planet Data see p. 412-415

Exploring the Outer Planets

(To boldly go where no human has gone before)

Observation equipment is sent out into space to explore distant areas of our solar system. Space probes are unmanned satellites or remote-controlled ‘landers’ that put equipment on or close to planets where no human has gone before. Probes have done remote sensing on Mercury and Jupiter, taken soil samples on Mars, landed on Venus, and studied Saturn’s rings up close.

The most recent probes to explore Mars are still there. They are Spirit and Opportunity. They are looking for evidence of water to determine if Mars at one time could have sustained life. The only place that has been explored by humans in space, other than our Earth is the Moon.

Apollo 11 was the first landing and there have been many others since. The next step is to establish a base for interplanetary manned missions to Mars.

Voyager Today (note: the following is extra info)

As of April 4, 2007, Voyager 1 is over 15.18×109 km or 101.4 AU from the Sun, and has thus entered the heliosheath, the termination shock region between the solar system and interstellar space, a vast area where the Sun's influence gives way to the other bodies in the galaxy. If Voyager 1 is still functioning when it finally passes the heliopause, scientists will get their first direct measurements of the conditions in the interstellar medium. At this distance, signals from Voyager 1 take more than thirteen hours to reach its control center. Voyager 1 is on a hyperbolic trajectory and has achieved escape velocity, meaning that its orbit will not return to the inner solar system. Along with Pioneer 10, Pioneer 11, and Voyager 2, Voyager 1 is an interstellar probe.

Voyager 2 launched on August 20, 1977. It is identical to its sister Voyager program craft, Voyager 1, but unlike Voyager 1, Voyager 2 followed a slower trajectory that allowed it to be kept in the ecliptic so that it could be sent to Uranus and Neptune by means of gravity assist during the 1981 encounter at Saturn. Because of this, Voyager 2 could not see the moon Titan up close like its twin, but it allowed the probe to become the first spacecraft to travel to Uranus and Neptune, thus completing a portion of the so-called Planetary Grand Tour, a rare geometric arrangement of the outer planets that only occurs once every 176 years.

Distribution of Space and Matter

Elliptical paths can help astronomers and scientists to trace and predict where bodies in space are, have been and will be in the future. The understanding of orbits has led to the discovery of many different comets. NASA tracks asteroids, comets and meteors that have been discovered by observatories and amateur astronomers. Astronomical unit is used for measuring ‘local’ distances in the solar system. It is equal to the distance from the center of the Sun to the center of the Earth (approximately 149,599,000 kms).

Light year is equal to the distance light travels in 1 year (approximately 9.5 trillion kms). It is used for longer distances – to stars and galaxies. The distance to our nearest star, Proxima

Centauri is a little over 4 light years.

Comets- a celestial body made of ice and dust that orbits the Sun. It has a bright centre and long faint tail that always points away from the Sun. (ex. Halley’s Comet- we see it every 76 years- its last pass was in 1986)

Meteors and Meteorites- a meteor is a piece of rock or metal that enters the Earth’s atmosphere and glows brightly from the friction. (Ex. Shooting stars) A meteorite is a meteor that has landed on the Earth’s surface.

Looking into the Past?

When you view an object in the sky you are seeing it as it was in the past. It has taken the light a very long time to reach the Earth. Light from the Sun takes about 5 minutes to reach the Earth, whereas light from Pluto takes about 5 hours. The farther away, the longer light takes to reach the Earth. Light from the stars in the center of the universe takes about 25,000 years to reach the Earth. The Hubble telescope is capturing light from 12 billion years ago.

Stars

Stars are born in a nebula. A star is a hot, glowing ball of gas (mainly hydrogen) that gives off light energy. Stars vary in their characteristics. Very hot stars look blue, while cooler stars look red. In the 1920’s, Ejnar Hertzsprung and Henry Norris Russell compared the surface temperature of stars with its brightness (luminosity). They graphed their data to show the relationship between brightness and temperature of stars was not random. The process of ‘star-building’ is known as fusion (when hydrogen is converted to helium), which releases great amounts of energy and radiation.

Topic 7 Assignment

Vocabulary:

Solar wind- High-energy subatomic particles that stream off the Sun and define the boundaries of the solar system.

Inner planet- the four planets closest to the Sun- Mercury, Venus, Earth, and Mars- sometimes called terrestrial planets because of their terrestrial, or rocky, composition.

Outer planet- The four planets furthest from the Sun- Jupiter, Saturn, Uranus, and Neptune- all have gaseous composition.

Proto-planet hypothesis-

Space probe-

Nebula-

NASA-

Fusion-

Comet-

Meteor-

Meteorite-

Use your notes and textbook to answer the following questions.

1. Write out the protoplanet hypothesis.

2. List 3 interesting facts about the Sun that you read about:

- The sun is so hot that the gas glows, it is the light from this gas that speeds through space to reach and warm earth.

- The surface of the sun constantly writhes and churns.

- Spectacular solar prominences are streamers of glowing gas that arch into space.

- Some regions on the Sun are cooler and therefore appear to be darker than their surroundings (Known as sun spots).

3. What is solar wind?

The outflow of particles is Solar Wind high-energy subatomic particles that stream off the sun and define the boundaries of the solar system. If a location in space “feels” the solar wind, it is considered to be in the solar system. Earth’s magnetic field protects us from the harmful effects of the solar wind.

4. When did the first astronauts land on the moon? Who were they?

The first astronauts landed on the moon in on July 17th, 1969- Neil Armstrong and Edwin Aldrin.

5. Complete the table using the data cards

| |Inner (Terrestrial) Planets |Outer (Jovian) Planets |

|Composition |Rocky |Gaseous |

|# of moons |Mercury: 0, Venus: 0, Earth: 1 and Mars: 2 |Jupiter: 17, Saturn: 18, Uranus: 21, |

| | |Neptune: 8, |

|Rings (yes/no) |No |Jupiter: no, Saturn: yes, Uranus: Yes, |

| | |Neptune: no |

|Size (big/small) |Mercury: 0.38 Earth-Diameters, Venus: 0.95 |Jupiter: 11.25 Earth-Diameters, Saturn: |

| |Earth-Diameters, Earth: 12756km Earth- |9.45 Earth-Diameters. Uranus: 4.01 |

| |Diameters, Mars: 0.53 Earth-Diameters. |Earth-Diameters, Neptune: 3.88 |

| | |Earth-Diameters |

|Surface Temperature |Mercury: 430degrees Celsius and night temp |Jupiter: -150 degrees Celsius, Saturn: -180|

|Hot/Cold |drop to -180degrees Celsius. Venus: |degrees Celsius, Uranus: -210 degrees |

| |460degrees Celsius. Earth: 14 degrees |Celsius, Neptune: -220 degrees Celsius. |

| |Celsius, Mars: -50 degrees Celsius. | |

6. Which planet is most similar to Earth? Why?

7. Venus is considered Earth’s twin, yet we would probably not survive on Venus. Why?

We would probably not survive on Venus because of its thick atmosphere of 96% carbon dioxide gas, 3.5% nitrogen, and other chemicals. The carbon dioxide is very efficient at trapping the solar radiation that falls on the planet’s surface.

8. How does the Sun release energy?

The sun releases energy by the sun’s own gravity and compressed its hydrogen so much that the temperature at the Centre of the sun is 15 million degrees Celsius. This temperature is high enough for a kind of nuclear reaction (fusion) to happen. 600 t of hydrogen are converted into helium per second this process is how energy is released.

9. Why do many of the inner planets show evidence of heavy cratering?

Because of the rocks and storms that happen on the planet’s also because of the planets’ composition.

10. What are Voyager I and II and why are they special.

Voyager I and II are two space-crafts that were sent to the edge of the solar system with gravitational assists from the planets themselves. They are special because when scientist communicate with the voyagers (space-crafts) they must allow for a time lag. Even though the radio signals travel at the speed of light, it takes several hours for a signal to complete a round trip from Earth to the space-craft and back. By the start of the year 2002, the transmission time lag was over 23hours for voyage 1 and over 18hours for voyage 2. This time lag increases by about 1hour per year.

11. Why are comets called dirty snowballs?

Comets are called dirty snowballs because they are composed of dirty dust and rock that fall from the sky.

12. What is the difference between a meteor and a meteorite?

The difference between a meteor and a meteorite

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