Galaxies, Solar Systems and Motion (35B/36A) Galaxies are massive systems of stars, solar systems, remnants of stars, gas and dust, and dark matter held together by gravity. Supermassive black holes are at the center of most galaxies and have the greatest mass in their galaxy. Galaxies move because of gravity. Galaxies in the universe are categorized by their appearance: elliptical, spiral (ex. our Milky Way galaxy), or irregular.

Elliptical Galaxies-largest types of galaxy

Spiral Galaxies-most common type of galaxy

Irregular Galaxies-smallest types of galaxy

Lenticular Galaxies (Spiral is turning into an elliptical galaxy)

Our solar system is located in one of the “arms” of the Milky Way.

Know the names and order of the planets.

Galaxies, Solar Systems and Motion Why can’t orbits be anything other than circular or like an oval?

Galaxies, Solar Systems and Motion The gravitational pull of larger objects like stars brings smaller objects like planets into a circular/oval orbit around it. Gravity is always at work and never “stops working” so the shape of an object’s orbit can’t have any corners.

Based on the picture of the solar system, what 2 factors contribute to gravitational pull? Gravitational pull is DIRECTLY PROPORTIONAL to mass and INVERSE to distance. As mass increases, gravitational pull increases. As distance increases, gravitational pull decreases. As mass decreases, gravitational pull decreases. As distance decreases, gravitational pull increases.

Which of the terrestrial planets has the most gravitational pull?

All of the planets feel a HUGE gravitational pull from the sun so why don’t any of the planets get pulled into the sun?

1 AU = distance from Earth to the sun = 93 million miles! Answer: Distance! In the solar system, we measure distance in space by astronomical units (AU) 1 AU = distance from Earth to the sun = 93 million miles! To scale down distance, we can choose a number (for example 10 cm) to equal 1 AU and multiply that scale value to the AU of other planets to give us that planet’s diameter value. Planet AU Distance Scale Value Mercury .4 AU 4 cm Venus .7 AU 7 cm Earth 1 AU 10 cm

How can we make a model of the solar system if everything is so large? Planet Representative Object Actual Diameter Scaled Diameter Value Mercury 4,789 km Venus 12,104 km Earth 12,792 km Mars 6,779 km Jupiter 139,822 km Saturn 116,482 km Uranus 50,724 km Neptune 49,244 km Which of the representative objects and scaled diameters should each planet be matched to? The Sun’s diameter is 1.4 million km and is represented by a gigantic beach ball 1,066 cm in diameter. A marble (3.5 cm) Rubber ball (13 cm) Soccer ball (35 cm) Ping pong ball (5 cm) Basketball (85 cm) Volleyball (37 cm) Beach ball (105 cm) A golf ball (12 cm).

How can we make a model of the solar system if everything is so large? Planet Representative Object Actual Diameter Scaled Diameter Value Mercury Marble 4,789 km 3.5 cm Venus A golf ball 12,104 km 12 cm Earth Rubber ball 12,792 km 13 cm Mars Ping pong ball 6,779 km 5 cm Jupiter Beach ball 139,822 km 105 cm Saturn Basketball 116,482 km 85 cm Uranus Volleyball 50,724 km 37 cm Neptune Soccer ball 49,244 km 35 cm Which of the representative objects and scaled diameters should each planet be matched to? The Sun’s diameter is 1.4 million km and is represented by a gigantic beach ball 1,066 cm in diameter.