Which types of EM waves are most likely used to detect distant stars and galaxies? Why?

Radio waves

Explanation:

Electromagnetic waves consist of periodic oscillations of electric and magnetic fields in a plane perpendicular to the direction of propagation of the wave.

Electromagnetic waves are the only waves able to travel in a vacuum, where they travel with a speed of

(speed of light).

Electromagnetic waves are also classified into 7 different types, depending on their wavelength.

From shortest to longest wavelength, we have:

Gamma rays

X-rays

Ultraviolet

Visible light

Infrared

Microwaves

Radio waves

Radio waves are the EM waves with longest wavelenght, spanning from a few meters to several kilometers. Because of this property, radio waves are able to travel across long distances without being absorbed by anything: so, they are used to detect distant objects such as stars and galaxies, due to this property.