Solar System Overview

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Questions and Answers

What is the primary unit of distance used in astronomy?

Light-year (correct)

Light-hour

Light-week

Light-minute

How far is the Moon from Earth in light-seconds?

1.28 light-seconds (correct)

2.5 light-seconds

1.50 light-seconds

0.5 light-seconds

What is the estimated size of the Milky Way Galaxy in light-years?

75,000 light-years

120,000 light-years

50,000 light-years

100,000 light-years (correct)

How long ago is it estimated that the sun and solar system formed?

4.6 billion years ago Signup and view all the answers

What is the speed of light in kilometers per second?

300,000 km/s Signup and view all the answers

What distance is described as 1 light-year?

The distance light travels in one year Signup and view all the answers

How large is our solar system in light-hours?

11 light-hours Signup and view all the answers

What is the approximate distance to the known universe that is observable from Earth?

12 billion light-years Signup and view all the answers

What is the shape of Earth's orbit around the Sun?

Elliptical Signup and view all the answers

What is the average distance from Earth to the Sun?

150,000,000 km Signup and view all the answers

When does Earth reach perihelion, the point when it is closest to the Sun?

January 3 Signup and view all the answers

What causes sunspots?

Magnetic storms on the Sun Signup and view all the answers

What is the cycle duration of sunspot activity?

11 years Signup and view all the answers

How long does it take for solar wind to reach Earth?

3 days Signup and view all the answers

What is the primary process generating solar energy?

Nuclear fusion Signup and view all the answers

What are auroras caused by?

Electrically charged particles from the solar wind Signup and view all the answers

What phenomenon occurs when both hemispheres experience equal amounts of daylight and darkness?

Equinox Signup and view all the answers

During which season is the Northern Hemisphere tilted away from the sun?

Winter Signup and view all the answers

What does axial parallelism refer to in the context of Earth's orbit?

The axis maintains its tilt and alignment during orbit Signup and view all the answers

What factor affects the increase of insolation at the equator compared to the poles?

Sphericity of Earth Signup and view all the answers

What is the rotational velocity of Earth at the equator?

1674 km/h Signup and view all the answers

At what angle does the plane of the ecliptic deviate from the equator?

66.5 degrees Signup and view all the answers

What happens to day length in the hemisphere tilted towards the sun during summer?

Day length increases Signup and view all the answers

When is Earth at perihelion in relation to the Southern Hemisphere's summer?

January 3 Signup and view all the answers

What is the thermopause in relation to Earth's energy system?

The outer boundary of Earth's energy system Signup and view all the answers

How much more concentrated is insolation in the Tropics compared to the poles?

More than 2.5 times Signup and view all the answers

What does the subsolar point represent?

The location where insolation is perpendicular to the surface Signup and view all the answers

Which physical factor does NOT contribute to the variations in seasons?

Distance from the Sun Signup and view all the answers

Which statement is true about Earth's revolution around the Sun?

It takes 365 days to complete one revolution. Signup and view all the answers

What is the tilt of Earth's axis from the perpendicular to the plane of the ecliptic?

23.5 degrees Signup and view all the answers

During which months does the Southern Hemisphere experience summer?

November to January Signup and view all the answers

What angle does the subsolar point move between throughout the year?

23.5° North and 23.5° South Signup and view all the answers

What astronomical event occurs at aphelion?

Earth's farthest position from the Sun Signup and view all the answers

During which date does the Northern Hemisphere experience aphelion?

July 4 Signup and view all the answers

What is the subsolar point during the summer solstice in the Southern Hemisphere?

Tropic of Capricorn Signup and view all the answers

Which factor is NOT one of the five reasons for the change of seasons?

Precession Signup and view all the answers

What describes the condition when all places on Earth experience equal day and night?

Equinox Signup and view all the answers

At which position in its orbit is Earth closest to the Sun?

Perihelion Signup and view all the answers

What is solar radiation that reaches Earth at a horizontal plane called?

Insolation Signup and view all the answers

Which date marks the winter solstice in the Southern Hemisphere?

June 20 or 21 Signup and view all the answers

Study Notes

The Solar System, Sun, and Earth

Our solar system is part of the Milky Way Galaxy, a flattened disk containing over 400 billion stars.
Our solar system is roughly halfway from the Milky Way's center, located in the Orion Spur of the Sagittarius arm.
The sun, along with the solar system, formed more than 4.6 billion years ago.

Dimensions and Distances

Light-year: The distance light travels in one year. 1 light-year = 9.5 trillion km.
Light speed: 300,000 km/s.
Milky Way Galaxy: 100,000 light-years across.
Our Solar System: 11 light-hours across.
Moon: 1.28 light-seconds away.
Observable universe: Roughly 12 billion light-years in all directions.

Earth's Orbit

Earth's orbit around the Sun is elliptical.
Earth’s average distance from the Sun is 150 million km, and light takes 8 minutes and 20 seconds to reach Earth.
Perihelion: The point in Earth's orbit where it is closest to the Sun (January 3)—147,255,000 km.
Aphelion: The point in Earth's orbit where it is farthest from the Sun (July 4)—152,083,000 km.

Solar Energy

Solar energy: Radiant light and heat from the Sun.
Nuclear fusion: The process that generates solar energy in which hydrogen nuclei are joined, forming helium and releasing energy.

Sunspots

Sunspots: Dark areas on the Sun’s surface caused by magnetic storms.
Sunspots are more than 12 times the diameter of Earth.
Sunspots have a lower temperature than their surroundings.
Sunspots have an 11-year activity cycle.
Solar wind: A stream of energetic particles emitted from the Sun’s corona, often associated with sunspots.
Coronal Mass Ejection (CME): A large burst of plasma and magnetic field from the Sun’s corona.
Magnetosphere: Earth’s magnetic field that shields the planet from most of the solar wind.

Insolation Receipts and Earth’s Curved Surface

Insolation: Solar radiation that reaches Earth’s surface.
The thermopause (480km above Earth’s surface) marks the outer boundary of Earth's energy system.
Subsolar point: The location on Earth where the Sun’s rays strike directly at 90 degrees.
The subsolar point moves between the Tropics of Cancer and Capricorn, due to Earth's tilt.
Locations further from the subsolar point receive more diffuse insolation.

Causes of the Seasons

Revolution: Earth’s yearly orbit around the Sun.
Rotation: Earth’s daily spinning on its axis.
Tilt of Earth’s axis: The axis is tilted 23.5 degrees from the perpendicular to the plane of the ecliptic.
Equinoxes: Twice a year, the circle of illumination aligns with the lines of longitude, resulting in equal day and night for all locations (March 20/21 and September 22/23).
Axial parallelism: The tilt of Earth’s axis remains fixed as it orbits the Sun, meaning the North Pole points toward Polaris.
Sphericity: Earth’s shape, slightly flattened at the poles and bulging at the equator, affects the distribution of solar radiation.

The Four Seasons

Summer solstice: The day with the longest period of daylight in the hemisphere tilted toward the Sun.
In the Southern Hemisphere, this occurs on December 21 or 22.
Winter solstice: The day with the shortest period of daylight in the hemisphere tilted away from the Sun.
In the Southern Hemisphere , this occurs on June 20 or 21.
Midnight Sun: When the Sun remains above the horizon for 24 hours during the summer solstice at high latitudes.
Annual March of the Seasons: Earth’s position in its orbit around the Sun determines the intensity and duration of solar radiation received by each hemisphere throughout the year.

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Description

Explore the fascinating characteristics of our solar system, including its formation, dimensions, and the unique relationship between the Earth and the Sun. This quiz covers various aspects of astronomical distances and the intricacies of Earth's orbit. Test your knowledge about the Milky Way Galaxy and beyond!