Space Physics

• What causes day and night on Earth?

  The rotation of the Earth on its axis
• How long does one complete rotation of the Earth take?

  24 hours
• What determines which half of the Earth experiences day and which half experiences night?

  The half facing the Sun experiences day, while the half facing away experiences night
• How does Earth's rotation affect the apparent movement of the Sun?


  It causes the Sun to appear to move from east to west daily
• Where does the Sun rise and set during the equinoxes?


  The Sun rises exactly in the east and sets exactly in the west
• How does the Sun's rising and setting position change in the northern hemisphere during summer?

  The Sun rises north of east and sets north of west
• What happens to the Sun's rising and setting position in the northern hemisphere during winter?

  The Sun rises and sets south of the points it rises and sets in summer
• What causes the seasons on Earth?

  The Earth's motion around the Sun and the tilt of its axis
• How often does the Moon orbit the Earth?

  Approximately every month
• What is the average distance from the Earth to the Moon?

  About 400,000 km
• Why does the Moon always show the same side to the Earth?

  Because it revolves on its axis at the same rate it orbits the Earth
• What is the nature of the Moon's surface?

  The Moon reflects sunlight, has no atmosphere, and has a weaker gravitational field
• What are the phases of the Moon?


  The Moon's appearance changes during its monthly orbit
• What is a New Moon?

  The Moon is between the Sun and Earth, with the unlit side facing Earth
• What happens during the first quarter phase of the Moon?

  Half of the Moon is visible
• What is a Full Moon?

  The Moon is opposite the Earth from the Sun and is fully visible
• What are the waning phases of the Moon?

  They follow the full moon, leading to the last quarter and old crescent
• What is the formula for average orbital speed?

  Average orbital speed is given by $u =$$\frac{2\pi r}{T}$
• What does $r$ represent in the orbital speed formula?


  $r$ is the average radius of the orbit
• What does $T$ represent in the orbital speed formula?


  $T$ is the orbital period, or time for one orbit
• What path does the Moon travel in around the Earth?

  The Moon travels in a circular path around the Earth
• What is the distance traveled by the Moon in one orbit?

  The circumference of the circle, $2\pi r$
• What is the Solar System composed of?

  The Solar System contains the Sun, eight planets, dwarf planets, asteroids, moons, and smaller bodies like comets
• What are the inner planets of the Solar System?

  Mercury, Venus, Earth, and Mars
• What are the characteristics of the inner planets?

  They are small, solid, rocky, and have high density
• How did the inner planets form?

  They formed close to the Sun where it was too hot for gases to condense
• What are the outer planets of the Solar System?

  Jupiter, Saturn, Uranus, and Neptune
• What are the characteristics of the outer planets?

  They are much larger, colder, and mainly consist of gases
• How did the outer planets form?

  They formed in cooler regions where gases could condense
• What are asteroids?


  Pieces of rock of various sizes, mostly between Mars and Jupiter
• What happens to asteroids when they enter Earth's atmosphere?

  They burn up as meteors
• What are comets made of?

  Dust embedded in ice made from water and methane
• What happens to comets as they approach the Sun?

  They develop a bright long tail due to radiation pressure
• What type of orbits do planets, dwarf planets, and comets have around the Sun?

  They orbit the Sun in an ellipse
• Where is the Sun located in the orbits of planets?

  The Sun is at one focus of the ellipse, not the center
• How do the orbits of comets differ from those of planets?

  Comets have highly elliptical orbits, while planets' orbits are more circular
• How did the Solar System originate?

  It formed from gravitational attraction pulling together clouds of hydrogen gas and dust (nebulae)
• How long ago did the Solar System form?

  About 4500 million years ago
• How did the inner planets form from the nebula?

  They formed from materials with high melting temperatures like metals and silicates
• How did the outer planets form from the nebula?

  They formed from light molecules that existed in solid icy forms, capturing hydrogen