Electromagnetic Spectrum Radio telescopes make use of the wave nature of light to image the cosmos.

Radio light waves are a million times weaker than optical light waves. Yet they can travel right through walls and immense dust clouds in space. need giant telescopes and very sensitive electronic receiver/amplifiers 1 second energy output of a light bulb  100 Joules Energy received by a radio telescope in 1 second  0.00000000000001 Joules Optical and radio (blue) views of the nearby galaxy Centaurus A

Polarized Waves Linearly polarized electromagnetic wave moving through space. Red is the electric field, blue is the magnetic field. Linearly polarized wave: electric field oscillates in the vertical direction http://www.surendranath.org/Applets.html

Green Bank Radio Telescope, West Virginia, US 100 m diameter

Cellphones, wifi, satellite TV spoil radio astronomy!

Hubble Space Telescope

Interstellar dust clouds make stars behind them look redder and fainter

Sunsets

Why do you think the dust around these stars looks blue?

Polarized light from a giant dust cloud around a young star 800 light years away. Someday this dust may turn into planets! Radio telescope (ALMA) image of HD142527

Black Hole at our Galactic Center Event Horizon Telescope