Think of a sphere with many a star-
Don't think "galaxy"; that's just too far.
Instead think of stars of the same age
Though in life at a different stage.
Don't confuse my younger cousins with me-
They live elsewhere in the Galaxy.
With some aid, see my fuzzy luster,
For I am a !

For it is a Globular Cluster

Explanation:

These Globular clusters are not considered to be a galaxies because they bond gravitationally to orbiting galaxies like the Milky Way and their masses are relatively small.

In globular clusters, the stars are closed together and they are like 70times closer to one another in their solar neighbourhood.

A globular cluster is a spherical collection of stars that orbits a galactic core. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes, and relatively high stellar densities toward their centers.

a and b sometimes have a positive value

d₁ = displacement of tern from arctic to antarctic = 11000 miles

d₂ = displacement of tern from antarctic to arctic =   - 11000 miles

d = total displacement for the journey

total displacement for the journey is given as

d = d₁ + d₂

d = 11000 + (-11000)

d = 0 miles

t₁ = time of travel from arctic to antarctic = 3 months = 3 x 30 days = 90 days

t₂ = time of travel from antarctic to arctic = 3 months = 3 x 30 days = 90 days

t = total time of travel

total time of travel is given as

t = t₁ + t₂

t = 90 + 90

t = 180 days

average velocity is given as

average velocity = total displacement/ total time

v = d/t

v = 0/180

v = 0 miles/day