Radio telescope picks up the radio spectrum of electromagnetic waves from celestial bodies (just like telescopes like the Hubble pick up visible light – only that radio waves are invisible to our eyes). They are therefore used to detect objects in space that produces radio waves. Examples are quasars and pulsars. Radio telescopes also enable astronomers to be whats beyond gas and dust in space that blocks out most of the visible light spectrum.
Radio waves from space are sensed by a giant parabolic reflector which concentrates them toward the top of a focusing antenna. A radio receptor converts the radio waves into electrical signals which are amplified and then transmitted to the center of the parabola. They are then recorded and analyzed in the laboratory so that scientists can obtain a radio image of the source observed. The parabolic antenna can usually be oriented to detect radio waves from all directions of space.
<em>Most trees do 'slow down' during winter, and deciduous trees that lose their leaves shut down photosynthesis entirely. Trees with needles (evergreen trees) that are retained over winter can actually photosynthesize during the winter.</em>
