The Milky Way
The Milky Way Galaxy
• A broad, faintly glowing band stretching
across the night sky.
Composed of billions of stars in our galaxy
too faint to be seen individually.
It’s invisible when the sky is lit up by artificial
light or bright moonlight.
Galaxies
Galaxies
• Galaxies are systems of stars, gas and
dust
• They exist in a wide variety of shapes and
sizes
• 4 basic types - elliptical, spiral, barred
spiral, and irregular
Elliptical Galaxies
• About 60% of the galaxies
• Are round to oval in shape
Spiral galaxies
• have a central nucleus surrounded by a
flattened disc with the stars, gas, and dust
organized into a pattern of spiral arms.
• Greater concentration of stars near their centers
Barred Spiral
Has a bar through the center with arms extending
through the bar
Irregular Galaxy
These galaxies have little symmetry in their structure
About 10% of the galaxies