international astronomical union / office of astronomy for development kevin govender –...

International Astronomical Union / Office of Astronomy for Development

Kevin Govender – kg@astro4dev.org

J.-C. Mauduit – jcm@astro4dev.org

OAD

www.astro4dev.org

IAU: International Astronomical Union

NRF: National Research Foundation

Dr. Jean-Christophe MauduitIAU Office of Astronomy for Development

From planets to superclusters of galaxies

The different scales of the Universe

National Research Foundation

From the Solar system to the Milky Way…

The blue planet: Earth

Radius ~ 6 378 km Atmosphere < 600 km

Troposphere < 15 km

From the Earth to the Moon

Earth-Moon distance: 384 401 km

30 Earth planets one after the other

~ 2 months of high speed train

Apollo missions : less than 2 days

(Speed of ~ 8000 km/h to ~ 40 000 km/h)

Space shuttle take-off

The crescent Earth from the Moon

You are here !

As imaged from the red planet, Mars

Our star, the Sun

Characteristics:

Radius~ 695,000 km

Mass = 1.9891×1030 kg

Volume = 1.41×1018 km³

Luminosity = 3.827×1026 W

Comparison to Earth:

109 × Earth

332 950 × Earth

1 300 000 × Earth

9.15 × 1016 tons of TNT / s

Distances in the Solar system

The astronomical unit (A.U.) is the Earth-Sun distance :

1 A.U. = 149 597 871 km

Voyager,The furthest probe sent by humans is at 12,5 billion kilometres of the Earth, hence 82 A.U. of us…

Sun 0 109

Mercury 0,39 0,38

Venus 0,72 0,95

Earth 1,0 1,00

Mars 1,5 0,53

Jupiter 5,2 11

Saturn 9,5 9

Uranus 19,2 4

Neptune 30,1 4

Pluto 39,5 0,18

MassDistance

The Solar system, as seen from the Voyager probe

Credits : Sonde Voyager

The speed of light

The Sun is at~ 8 light-minutes

The Voyager probe is at ~ 12 light-hours

c ~ 300 000 km/s

Light-minutes Astronomical Units

Average planet distances to the Sun

1 Light-year = 63240 Astronomical Units = 9,46 x 1012 km

The stars in the sky are similar to our Sun

But so far away that we see them as points of light

• Located at 4.22 Light-year from the Sun.

• Its light takes about 4 years to reach us

Proxima Centaurus,The closest star from our Sun

Stars sometimes form clusters

Messier 3 (M3) Star cluster

D (Sun– M3) ~ 34 000 light years

Before AfterThe Milky Way

The city sky

A little geography of our Milky Way

Magellanic cloudsGalactic bulbSpiral arms

The Milky Way, as seen from the inside

Two satellite galaxies of the Milky Way

The extragalactic domain

The extragalactic « nebulae »

M75

Star clusters belong to our

Galaxy

M32 M101

But these other diffuse objects are

galaxies

Voie LactéeVoie Lactée

Petit nuage de Magellan

Grand nuage de Magellan

Voie Lactée

Petit nuage de Magellan

Grand nuage de Magellan

Voie Lactée~ 160 000 l.y.~ 2.5 million l.y..

~ 200 000 l.y.

Our greatest neighbor, the “Andromeda” galaxy

D (Milky Way – M31) ~ 2.5 million l.y.r ~

50000 l.y.

M31 fait partie du groupe “ Local ” de galaxies …

1 Million Light Years

Our Galaxy

From Earth…

To the Local Group of galaxies

M74 : 30 million l.y.

Sombrero : 40 million l.y.

A compact group

500 000 l.y.

Hickson compact group 79

Virgo cluster

At ~ 60 Million Light Years

10 million l.y.

The large-scale structure of the Universe

Abell cluster 1689

10 million l.y.

Hubble Ultra-Deep Field

How many galaxies on this image?

!

2D view of galaxies in the sky as observed in infrared

… to the large-scale structure of the Universe

From the Perseus cluster…

~ 1 B

illion l.y

.

Large galaxy surveys generally focus on small portions of the sky

3D Diagram

~ 163 million l.y.

Scale:

100 Million l.y.

~ 26

0 M

illion

s l.y

.

The local group of galaxies within the local supercluster

The most distant galaxies ever observed

~ 11 Billion years

The “most distant” picture of the Universe at its “youngest”

The “beginning” of the Universe

Thank you!

Vidéos et Images d’astronomie

Loi de Hubble (1929)

v= H0 d

Edwin Hubble

Galaxie proche :

Galaxie distante :

From the ground

From space

M51 and its companion

Pairs of galaxies

In this computer simulation, one can see the formation of the large scale structures of the Universe

Groupe de galaxies : des galaxies en intéraction ?

Du visible … à la radio !

Elliptiques

Spirales

Les différents types de galaxies

simples

barrées