# planet orbits in the solar system

## the size and shape of orbits

Figure 1.1 shows the relative sizes of the orbits of the planets, asteroid belt, and Kuiper belt. In general, the farther away from the Sun, the greater the distance from one planets orbit to the next. The orbits of the planets are not circular but slightly elliptical, with the Sun located at one of the foci (see opening image). While studying the solar system, Johannes Kepler discovered the relationship between the time it takes a planet to make one complete orbit around the Sun, its "orbital period," and the distance from the Sun to the planet. If the orbital period of a planet is known, then it is possible to determine the planets distance from the Sun. This is how astronomers without modern telescopes could determine the distances to other planets within the solar system. How old are you on Earth? How old would you be if you lived on Jupiter? How many days is it until your birthday on Earth? How many days until your birthday if you lived on Saturn? Click image to the left or use the URL below. URL: The relative sizes of the orbits of planets in the solar system. The inner solar sys- tem and asteroid belt is on the upper left. The upper right shows the outer planets and the Kuiper belt.

## instructional diagrams

No diagram descriptions associated with this lesson

## questions

the seasons are caused by

``````a) earths orbit around the sun.

b) annual changes in solar radiation.

-->  c) the tilt of earths axis.

d) changes in atmospheric circulation.
``````

what is the shape of a planets orbit?

``````a) circular

b) triangular

c) rectangular

-->  d) elliptical
``````

who discovered the relationship between a planets orbital period and the distance from the sun?

``````a) nicolaus copernicus

-->  b) johannes kepler

c) isaac newton

d) galilieo galilei
``````

the planet in the solar system with the largest orbital period is

``````a) mercury

b) earth

c) jupiter

-->  d) neptune
``````

the closer two adjacent planets are from the sun, the farther the distance from one planets orbit to the other.

``````a) true

-->  b) false
``````

mars has the smallest orbit in our solar system.

``````a) true

-->  b) false
``````

the time it takes a planet to make one complete orbit around the sun is known as its __.

``````-->  a) orbital period

b) time of revolution

c) elliptical period

d) speed
``````

if the asteroid belt is a planet that didnt come together, we would expect the asteroids to be the right orbital distance between mars and jupiter.

``````-->  a) true

b) false
``````

how did scientists determine a planets distance from the sun before the invention of modern telescopes?

``````a) the distance is directly related to the amount of time it takes for the planet to rotate once on its axis.

b) by observing the size of the planet.

-->  c) the distance is directly related to the planets orbital period.

d) none of these.
``````

scientists now must know exactly where a planet is and will be in the future if they are going to send spacecraft to see it.

``````-->  a) true

b) false
``````

## diagram questions

No diagram questions associated with this lesson