Question

1. how do scientists use the types of spectra when studying objects in space? to study an objects size and gravitational pull to study the age of the object and its gravitational pull to study an objects composition and movement to study an objects direction of rotation and length of revolution

Explanation:

Spectra can reveal an object's chemical - element composition through spectral lines. Doppler shift in spectra can show an object's movement (towards or away from the observer).

Answer:

to study an object's composition and movement