Lesson Two - Muggle-made Tools:

Telescopes

Optical instruments that magnify distant objects and make them appear brighter. They are astronomers most important tool and were used to discover Uranus, Neptune and Pluto.

Edwin Hubble examined the colour of light from distant galaxies with the 100-inch wide Hooker telescope and was able to conclude the universe was expanding. Starting a branch of astronomy known as cosmology that studies the origin and evolution of the universe. 

Earliest telescopes had two lenses at opposite ends of a tube. At the far end is the light-gathering lens called the objective lens. This lens is conves (thicker in the middle than edges) like a magnifying glass and is called a positive lens. To make images appear clear the other lens (eyepiece) is a concave (thinner in the middle and thicker at the edges) it is called a negative lens.

Galileo Galilei improved on that design two years later. He found that making the objective lens less curved you could improve the magnifying power from 3 to 20. He used it to discover the four largest moons of Jupiter. He also discovered that Venus has phases like the moon. This confirmed Copernicus's belief that the Earth revolves around the sun rather than the other way. 

Telescopes that use only lenses are called refracting telescopes. Isaac Newton invented the reflecting telescope in 1688 by using mirrors instead of lenses. 

The amount of light a telescope gathers is based on area not diameter. The observed closeness of two points of light is measured as an angle not a straight line. Ancient greeks divided a circle into 360°, so if one star is on the eastern horizon and the other on the wast they would be 180° apart. Someone with an average vision can distinguish two points of light about 1/20th of a degree apart with the naked eye at best. Astronomers need to see things that appear much closer than that so they use special measurements known as arcminutes and arcseconds (degrees usually are divided into minutes and seconds). A degree is divided into 60 arcminutes and an arcminute is divided into 60 arcseconds.

Satellites

Moons are natural satellites. 

GPS - Global Positioning System

The Hubble is about 2.5 meters wide. It is able to resolve two stars 0.05 arcseconds apart. It was launched in 1990.

Satellites sometimes carry tools like cameras, radars, and remote sensors. Tools to collect and analyze space particles and other important information. 

The first satellite was Sputnik (meaning'fellow traveler' in Russian) released by the Soviet Union in 1957. Four months later the United States launched their first satellite Explorer 1. The Soviet Union however had already launched their second satellite including the dog Laika. Shortly after they launched a third with the first man in out space Yuri Gagarin. 

In 1958 America created the National Aeronautics and Space Administration (NASA). America won the space race in 1969 when they sent Neil Armstrong and Buzz Aldrin to land on the moon and were able to bring them safely back to Earth.

In 1963 Valentina Tereshkova was the firt woman in space and spent three days there. NASA launched their first woman Sally Ride twent years later. 

Space Agencies in Other Countries

Several European countries contribute to the European Space Agency. Several other countries also have agencies including Canada, India, Japan and China. 

China National Space Administration first landed a rocket on the far side of the moon on January 3, 2019.

Russians, Canadians, Americans, Japanese and Europeans cooperated to build the International Space Station (ISS).

Space Shuttles

NASA began a program called the Space Transportation System in the 1980s. They used space shuttles to launch numerous other satellites, interplanetary probes, and the Hubble Space Telescope and to help construct and service the ISS. The program was terminated in 2011 and NASA began using the Russian spacecraft Soyuz for these things.

Radar

Radar is a detection system that uses radio waves to determine the range, angle, or velocity of objects. Many astronomical objects have been studied by radar including the moon, Mercury, Venus, Mars, the four largest moons of Jupiter, Saturn's rings and its moon Titan and, a few nearby comets and asteroids. Radar lets astronomers get information about the surface of these objects.

Rovers 

Rovers are vehicles that are designed to move across the surface of a planet or moon. They study the planet or moon by taking pictures, samples of dust and rocks and, readings of the atmosphere. Rovers have only landed on Mars or the moon so far. All but one Yutu (a Chinese lunar rover) are American or Russian.

One Mars rover Curiosity is currently searching for evidence of past and present life in the planet. 

Rovers can be driven from Earth if they are on the moon because it only takes one and a quarter seconds for a signal to travel from Earth to the moon. However, rovers on Mars have to be self driving as signals can take between four and twenty-four minutes to travel from Earth to Mars.