2. Introduction
• The scientific study of matter in outer
space especially the positions,
dimensions, distributions, motions,
energy and evolution of celestial bodies
and phenomena is known as astronomy.
• Mainly, all the objects present in the
space are classified into 2 groups known
as luminous and non-luminous.
• The next slide explains more about it.

3. • Luminous objects:
Objects that emit their own light are
known as luminous objects. For eg; Sun,
Stars.
• Non- Luminous Objects:
Objects that do not emit their own
light and reflect the light from luminous
objects. For eg; Moon, Planets.
Many people think that
Moon is a luminous object as it is bright in
the night, but it reflects the light rays of
the Sun.