The Sun- Earth- Moon

SystemChapter 28

Section 28-1TOOLS OF ASTRONOMY

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

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

• 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

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

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

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

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

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

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

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

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

THE MOONSection 28.2

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

Lunar Properties