Astronomy 101Astronomy 101GalaxiesGalaxies

Galaxy Concept

1755 Immanuel Kant

Vast collections of stars outside the Milky Way

William Parsons- (Lord Rosse) 72” scope in 1850’sSpiral structure in in Hershel’s Nebulae

M51

1920 Shapley-Curtis Debate

CurtisSpiral Nebulae were Island Universes

ShapleySpiral Nebulae were close objects in our galaxy

Hubble 1924

Found Cepheid Variables in M-31

Could Determine Distances

Types of Galaxies

Spiral

Barred Spiral

Elliptical

Irregular

Pecular

Spiral M81 in Ursa MajorSpiral M81 in Ursa Major

Closest spiral is M-31Closest spiral is M-31

Where’s Waldo?

Barred Spirals Barred Spirals

Milky Way is Barred SpiralAPOD April 23, 2015

Elliptical M32 by Greg HigginsElliptical M32 by Greg Higgins

Irregular- Colliding GalaxiesIrregular- Colliding GalaxiesWhat about the stars?What about the stars?

M51 by Mike Heim

Milky Way and Andromeda

Collision in 6 billion years

Peculiar M82 by J &R McCullough

Hubble’s Tuning Fork SchemeHubble’s Tuning Fork Scheme

Galaxy Clusters

Virgo

Cluster

Active Galaxies

Brighter than ordinary galaxies

10% of all galaxies

Talk for another time….

Hubble Ultra Deep Field Video