1. Solar system
2. Stars
3. Milky Way
4. Galaxies
5. Clusters and super-clusters
6. Cosmological principle (homogenous and isotropic)

How big is the Universe

How big is the Universe

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Terrestrial Planets

Terrestrial Planets

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Jovian Planets

Jovian Planets

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Newborn stars emerging
from "eggs" — not the
barnyard variety — but
rather, dense, compact
pockets of interstellar
gas called evaporating
gaseous globules
(EGGs). Hubble found
the "EGGs,"
appropriately enough, in
the Eagle nebula, a
nearby star-forming
region

7,000 light-years

from Earth in the
constellation Serpents

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One of the
nearest globular
star clusters,
called NGC 6397,
resembles a
treasure chest of
glittering jewels.
The cluster is
located

8,200

light-years

away

in the
constellation Ara.

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Stellar swarm, M80
(NGC 6093), one of
the densest of the
147 known globular
star clusters in the
Milky Way Galaxy.
Located about

28,000 light-years

from Earth, M80
contains hundreds
of thousands of
stars, all held
together by their
mutual gravitational
attraction.

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Large Magellanic Cloud
165 000 LY

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Small Magellanic Cloud
195 000 LY

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The Sagittarius Dwarf Tidal Stream
Drawing Credit & Copyright: David Martinez-Delgado (MPIA) & Gabriel
Perez (IAC)
2003 September 30

Explanation:
Our

home galaxy

is actually still in the process of devouring its closest

satellite neighbor

.

This unfortunate neighbor, the

Sagittarius Dwarf

galaxy, is now seen to

be part of a larger

Sagittarius Tidal Stream

, a loose filament of stars,

gas, and possibly dark matter that entangles the

Milky Way

.

Speculation also holds that the Sagittarius Dwarf was once pulled
through the Milky Way disk very close to our Sun's current location.

NGC 1313,

(13.5 M light years)

a bright but rather isolated

galaxy classified as a barred spiral galaxy (although with very
short and irregular spiral arms). This galaxy collided with a
satellite galaxy, and the material at the bottom-right of this
picture are the remains of the satellite galaxy.

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Spiral galaxy NGC 4414
19.1 megaparsecs

(60 M LY)

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Galaxies tend to cluster into groups - the largest nearby
cluster is the Virgo cluster a concentration of several
hundred galaxies which dominates the galaxy groups
around it.
Our galaxy is just one of thousands that lie within 100
million light years.
All of these groups of galaxies are known as the Virgo
Super-cluster.

Number of galaxy groups within 100 million light years

= 200

 

Number of large galaxies within 100 million light years

= 2500

 

Number of dwarf galaxies within 100 million light years

= 25000

 

Number of stars within 100 million light years = 200

trillion

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The Virgo Cluster

The Virgo cluster is a massive cluster of galaxies which dominates
the Virgo super-cluster. There are roughly

2000 galaxies

in this

cluster (although ninety percent of them are dwarf galaxies). This
cluster has a diameter of approximately

15 million light years

.

The centre of the cluster showing the inner 4°x 4° region. Most of the brightest
objects in this picture are galaxies.
The elliptical galaxy in the centre is M87.

M 87

M 90

M 89

M 84

M 86

M87 from the Hubble Space Telescope

 

                                                                                              

    

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Hubble telescope was used to observe 19 galaxies out to

108 million

light-years

. The spiral galaxy NGC 4603, the most distant galaxy in

which Cepheid variables have been found. It is associated with the
Centaurus cluster, one of the most massive assemblages of galaxies
in the nearby universe.

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A rare and spectacular head-on collision between two galaxies

appears in this Hubble telescope picture of the Cartwheel Galaxy,
located

500 million light-years

from Earth in the constellation

Sculptor.
The striking ring-like feature is a direct result of a smaller intruder
galaxy

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Number of super-clusters in the visible universe = 10 million

 

Number of galaxy groups in the visible universe = 25 billion

 

Number of large galaxies in the visible universe = 100 billion

 

Number of dwarf galaxies in the visible universe = 10 trillion

 

Number of stars in the visible universe = 20 billion trillion

The Hubble Deep Field

Almost every object in this image is a galaxy typically lying

5 to 10 billion light years

away.

The galaxies revealed here are all shapes and colors, some are young and blue,
whereas others are old, red and dusty.

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The Visible Universe

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