How Stars are Seen… Astronomy - Ch.20

Naked Eye can see ≈ 5000 stars

The Optical Telescope gathers light by focusing it through a lens or mirror – now we can see many more stars!

The Optical Telescope COLLECTS LIGHT: over minutes or hours to create digital or chemical photography Enables DISTINCTION between distant objects MAGNIFIES the images formed

The Refracting Telescope Using a large glass lens (objective) the light is refracted (bent) to a small lens (eyepiece) Light travels through the glass lens Ex: Binoculars, Small Telecsopes

The Reflecting Telescope Uses a curved mirror to gather and focus the light Largest optical telescopes are reflecting telescopes Ex: Hubble Space Telescope

The MMT (Multiple Mirror Telescope) Several small, low-cost mirrors replace on expensive large mirror Less expensive to build than telescopes requiring one large mirror The MMT (Multiple Mirror Telescope)

The Schmidt Telescope Combination of refracting-reflecting telescope with a wide field of view Found at almost all observing sites

The Hubble Space Telescope Designed to orbit high above the interference of Earth’s atmosphere, therefore very clear images Size of railroad boxcar 610 km above Earth’s surface

Beyond Visible Light We can use optical telescopes to study the visible light from stars, but not all forms of energy are visible Stars emit x-rays, radio waves, infrared waves and other kinds of electromagnetic energy

The Electromagnetic Spectrum ELECTROMAGNETIC ENERGY Forms of Energy that travel at the speed of light (300 000km/s), each with its own frequency and wavelength ELECTROMAGNETIC SPECTRUM Total range of electromagnetic waves, from radio waves to gamma rays