Ch. 27

Tools of Astronomy Scientists study the electromagnetic radiation given off by objects in our universe. Electromagnetic radiation travels as waves. This makes up the electromagnetic spectrum.

The electromagnetic spectrum is classified by wavelength and frequency. Frequency = c/ג c = speed of light (3.0 x 108 m/s) ג = frequency

Types of telescopes: Refracting – uses lenses to focus visible light.

Reflecting telescope – uses lenses and mirrors to focus light.

Some telescopes can detect radiation outside visible light such as infrared, radio, and gamma. Computers can be used to make a composite image using data from several types of telescopes. This is called an interferometer.

Sometimes smaller telescopes can be linked together to make one large telescope like the VLA.

https://www.youtube.com/watch?v=R qX9vLj3_7w

Sometimes telescopes are placed in outer space Sometimes telescopes are placed in outer space. This a allows them to escape the problems caused by looking through the atmosphere. The Hubble Space Telescope.

Sometimes scientist send probes to distant objects to get better information about the object which may be too distant or small to see with other telescopes.

Section 2 – The Moon July 20, 1969 – Apollo 11, Neil Armstrong and Buzz Aldrin land on the moon. 12 people have walked on the moon.

When you look at the moon you are seeing light reflected from the sun When you look at the moon you are seeing light reflected from the sun. The amount of sunlight its surface reflects (the albedo) is only about 7% compared to the Earth’s which is about 31%

The moon has no atmosphere The moon has no atmosphere. Temperatures vary widely between the light and dark sides. Light side can be 260 degrees F. Dark side can be -387 F.

The lunar surface has highlands that are heavily cratered, light in color and mountainous. Maria are dark areas which are mostly smooth and lower in elevation. They contain rills which are valley-like structures that may be lava tubes.

There are many impact craters on the moon There are many impact craters on the moon. Fallout from a crate is called ejecta and leave spoke-like trails called rays emanating from the crater. The moon and Earth are about the same age, 4.5 billion years old and have similar composition.

Formation – the most widely accepted theory is the Giant Impact Theory Formation – the most widely accepted theory is the Giant Impact Theory. It says the earth collided with a Mars sized object (Theia)

The Earth-Moon system. The Earth is tilted at 23.5 degrees. Because of this we have seasons. Solstices - Summer solstice occurs around June 21 and marks the beginning of summer. It is also the longest “day”.

Winter solstice occurs around Dec. 21 Winter solstice occurs around Dec. 21. It marks the beginning of winter and is the shortest “day” of the year. Equinoxes – Vernal equinox marks the beginning of spring. Occurs around March 21st. Marks the beginning of spring. Equal amounts of day and night.

Autumnal equinox – marks the beginning of fall Autumnal equinox – marks the beginning of fall. Occurs around September 22.

Tides are caused by the gravitational pull on the Earth by the moon Tides are caused by the gravitational pull on the Earth by the moon. They are also affected by the sun. Spring tides occur when the Sun and Moon work together to create a very high tide. Neap Tides are when the Moon and Sun cancel each other out and results in no measurable tidal difference.