Transcript Galaxies2 powerpoint


What is a galaxy?

It is a collection of billions/millions of stars,
planets, dust and gas held together by
gravity.

Turn to a partner and discuss:
 What are two kinds of optical/visible light
telescopes scientists use to gather information
from space?
 How do you think instruments using the
electromagnetic spectrum would allow scientists
to view space differently than using a refractor or
reflector telescope?

Approximately 8.5 light-years away

Light-year: 6 trillion miles

Goal:
 I can analyze how galaxies are classified.
 I can identify characteristics of our Milky Way galaxy.





Lab Group Classification Activity
Discuss classifications and re-group
Tree map notes
Exit Ticket
Galaxy Homework

Galaxies are huge groupings of stars, gas and
dust held together by gravity.

Galaxies differ greatly in size.
 Some contain a hundred million stars to the largest
containing more than a trillion stars!

Scientists classify galaxies.

The Hubble Space Telescope has just received
exciting new images of 30 galaxies. Your job is
to work with your team of scientists to classify
these galaxies.

Classify the 30 galaxies in your envelope
whatever kind of groups you decide.
 You must provide reasoning for your classification.
 Your team must record the categories and evidence
for support on your lab sheet.

Scientists classify into 3 categories by shape
 Spiral
 Elliptical
 Irregular
Spiral galaxies have arms
of stars, gas and dust that
curve away from the center
in a spiral or pinwheel pattern.


Spiral galaxies are disk-shaped, have a bulge in
the center.

Most of the stars in the disk & bulge are older
stars. However, the spiral arms within the disk
contain many young, bright stars.

In addition to the spiral galaxy, there is a
barred spiral. This type of galaxy is similar in
make-up to a spiral galaxy but seems to have
its arms connected or linked by a bar.

Elliptical galaxies are shaped like spheres to
football or egg-shaped. Unlike spiral galaxies,
elliptical galaxies have almost no dust or gas
between stars and all of their stars are old.

Irregular galaxies
are galaxies
without a
definite shape.
They are
generally smaller
than the other
type of galaxies
and contain
fewer stars.






Work with your team to reclassify your
galaxies.
Distinguish between barred spiral and spiral
galaxies.
Spiral
Barred Spiral
Elliptical
Irregular
Spiral
Barred Spiral
2, 5, 8, 10, 9, 27, 30
15, 16, 18,
19, 21, 25,
28, 7, 14, 20
ES: 7, 14,
20
Elliptical
Irregular
3, 6, 13, 23, 1, 4, 11, 12,
17, 22, 24,
26
29
Spiral
*Pinwheel
Shape
Barred Spiral
*Similar to
Spiral galaxy
*Arms of stars,
*Arms
gas, and dust
connected by
that curve away
bar in center
from center
Has bulge in
center and diskshaped
Most stars in
disk are old
Spiral arms have
more young
stars
Young and old
stars are present
Elliptical
Irregular
*Shaped like
*No definite
spheres or eggs shape
*Mostly old
stars present
Almost no dust
or gas
*Smaller than
other galaxies
with fewer stars
Young and old
stars are present
Contains gas
and dust

Galaxies are huge groupings of stars, gas,
planets, and dust held together by gravity.

The Earth lies within the Milky Way Galaxy.

The Milky Way is a spiral galaxy and is 100,000 light
years across.

The bulge of densely packed stars at the center is
approximately 26,000 light years away from the sun.

The stars in the Milky Way orbit the galaxy’s center at
very high speeds, still it takes our solar system about
250 million years to complete one orbit. The age of
the Milky Way has been calculated to be about 13
billion years old.

It’s all about perspective

Most large galaxies seem to have super massive
black holes at their centers. At the center of the
Milky Way is theorized to be a black hole with the
mass of about 3 million times that of the sun.

A black hole is a place in space where gravity pulls
so much that even light can not get out. The
gravity is so strong because matter has been
squeezed into a tiny space. This can happen when
a star is dying.

The center of some galaxies
look very bright. This
brightness is attributed to
quasars.

Quasar stands for quasi-stellar
which means “seeming like a
star.” Quasars eject hot gas
from their centers giving off a
very bright light.

Goal:
 I can analyze how galaxies are classified.
 I can identify characteristics of our Milky Way
galaxy
1.
2.
3.
4.
5.
6.
What kind of galaxy is shown in image #1?
What kind of galaxy is shown in image #2?
What kind of galaxy is shown in image #3?
What kind of galaxy is shown in image #4?
What is the name of our galaxy and what shape is it?
Bonus: Name one characteristic of each of the galaxies in #1-4.
1
2
3
4
Exit Ticket 2/12
Name _________________________
1. What kind of galaxy is shown in image #1? ________________
2. What kind of galaxy is shown in image #2? ________________
3. What kind of galaxy is shown in image #3? ________________
4. What kind of galaxy is shown in image #4? ________________
5. What is the name of our galaxy? ________________________
1
2
3
4