1. The Sun- Earth- Moon System
Chapter 28

2. Tools of Astronomy
Section 28-1

3. Radiation
The radiation from the cosmos that scientists study is electromagnetic radiation
Electromagnetic (EM) radiation consists of electric and magnetic disturbances traveling through space as waves
The human eye can only sense a limited range of wavelengths, which is visible light

4. Radiation You may be familiar with some forms of EM radiation
UV rays, X rays, infrared, radio waves, microwaves
EM radiation is classified by:
Wavelengths- the distance between peaks on a wave
Frequency- number of waves or oscillations per second

5. Telescopes have many benefits for exploring space:
Detectors can be attached to observe all wavelengths, not just visible light
Telescopes bring more light to focus than the human eye, allowing observation of faint objects
Specialized equipment such as photometer, which measures intensity of visible light, can be used with a telescope
With the aid of imaging devices, telescopes can be used to make time exposures to detect objects are too faint for the human eye to see

6. Telescopes Two different types of telescopes are used:
Refracting telescopes use lenses to bring visible light to a focus
The largest lens on a telescope is the objective lens
Telescopes that bring visible light to focus with mirrors are called reflecting telescopes

7. Telescopes The majority of telescopes used today are reflectors
Most scientific telescopes are located in observatories far from city lights in higher elevations where less atmosphere will blur images

8. Telescopes at other Wavelengths
For all telescopes, the goal is to bring as much EM radiation to a focus
Interferometry is the process of linking separate telescopes together so that they act as one
The detail in the images that they produce improves the distance between the telescopes

9. Satellites, Probes, and Space-Based Astronomy
Astronomers often send instruments into space to collect information for many reasons
Earth's atmosphere blocks infrared radiation, uv rays, X rays, and gamma rays
When earth’s atmosphere does allow wavelengths to pass through, the images are blurred
Scientists can make close up observations and obtain samples

10. Satellites, Probes, and Space-Based Astronomy
The Hubble Space telescope (HST) makes observations in infrared and UV wavelengths
Other telescopes, like Far Ultraviolet Spectroscopic Explorer, the Chandra X-Ray Observatory, and Spitzer Space Telescope observe other wavelengths blocked by atmosphere

11. Spacecraft
Space-based exploration can be achieved by sending spacecraft directly to the bodies being observed
Robotic probes make close-up observations and sometimes land to collect information
The twin robots Spirit and Opportunity conducted experiments on Mars

12. Human Spaceflight
Exploring objects in space has been a top priority, but the effects of space are very intriguing
A multi-country space station called the International Space Station has been inhabited since 2000 to study long-term effects of space

13. Spinoffs Space exploration has benefited our society in many ways
NASA technologies that have been passed onto commercial industries for use are called spinoffs
More than 1400 technologies have been passed on

14. Section 28.2
The Moon

15. Reaching for the Moon Plans for lunar exploration began in the 1950s
The first step was taken in 1957 with the launch of the first satellite by the Soviet Union, Sputnik
Soviet cosmonaut Yuri A. Gagarin became the first human in space in 1961
The US’s Mercury project launched the first American Alan B. Shepard Jr. into space May 5, 1961
Project Gemini launched 2 person crews into space and on July 20, 1969 the Apollo program landed Neil Armstrong and Buzz Aldrin on the Moon

16. Lunar Properties