T-Cap Study-guide. With A BIG Thanks to Study island. Inquiry/tech. Stu Guide By Holden Bledsoe Section. 1. Identify a testable question
Stu Guide By Holden Bledsoe Section
Study Guide By Holden Bledsoe
The Sun shines on exactly one-half of the Moon, except during a lunar eclipse. From Earth, we can generally see only the part of the Moon that is lit by the Sun. As the Moon orbits the Earth (once about every 28 days), the amount of the lighted half of the Moon that we can see from Earth changes. These changes give us the phases of the Moon. The Moon makes one complete cycle every 29 1/2 days.
The way we tell time on Earth is based on the movement of the Earth and Moon in space. The three main units of time derived from these movements are the day, month, and year.
If you look at the night sky regularly during a year, you will notice small disks that change in brightness and position against the background of other stars. The Greeks called these wandering stars planets. We know that there are 8 official planets in our solar system (shown below): The inner planets (Mercury, Venus, Earth, Mars) and the outer planets (Jupiter, Saturn, Uranus, Neptune). The inner planets each orbit the Sun in less than 2 years, but the outer planets take from 12 to 164 years each to orbit the Sun.