Optics and the Universe

Furthermore, we will get an insight into some basic astronomy. Motivation Having covered some aspects of optics, we will use the gained knowlegde to explain phenomena such as eclipses of the Sun and of the Moon. Furthermore, we will get an insight into some basic astronomy.

How? We will take a look at the solar system, explaining everyday phenomena.

The Solar System The Earth is 1 of 8 planets that orbit the Sun. It takes the Earth 365,25 days to orbit the Sun. We call this a year. It takes, say, 687 days to orbit the Sun. Thje sizes of the planets are to scale. The distances between the planets are not to scale.

The Sun Surface temperature: 5500oC Central temperature: 15 mio. oC Radius: 109 times the radius of the Earth. 74,5 % Hydrogen; 23,9 % Helium

Do exercise 2, 3 and 6 on p. 72. Homework: ex. 4 on p. 72. The Planets The rocky planet Mars The gas giant Jupiter. Do exercise 2, 3 and 6 on p. 72. Homework: ex. 4 on p. 72.

The axis tilts by 23,44 degrees, which courses something else… The Earth, Day and Night The Earth spins around ist own axis once every day. This results in day and night. The axis tilts by 23,44 degrees, which courses something else…

The Earth, Seasons

The Moon The Moon orbits the Earth in a tilted, eliptical orbit once every month. When the Moon is closest to the Earth (perigee) it looks bigger (Supermoon) and is 363.000 km away. When it is furthest away (apogee), it is 392.000 km away.

The Moon Exercise: From Earth you can always see only one side of the Moon. In other words, the same side of the Moon always faces the Earth. What does this tell you? Exercise: Answer the question in the green box on page 74 and discuss the facts in the green 3 boxes on p. 74-75. Do exercise 1 on p. 77.

Phases of the Moon

Remember shadows? If the light source is larger than the object, the shadow has a fuzzy edge called a penumbra. The clear cut shadow is called an umbra.

Solar Eclipse

Solar Eclipse So, when the Moon comes between the Earth and the Sun. If you stand, where the umbra is, you see a total eclipse. In the penumbra, the Moon only partly covers the Sun. Exercise: Solar eclipses do not happen every month. Explain why.

Why do lunar eclipses not happen every month?

Blood Moon At a total lunar eclipse, mostly red light passes through the atmosphere. This light is reflected from the Moon. Therefore the Moon looks red. This is called a blood moon. Do exercise 2 and 3 on p. 77.

Sundown