Download Classifying Star Brightness

PG 15
 Put
the following in scientific notation
 3,457,000
 .0000245
 How
many constellations are in
Space?
Magnitude &
Brightness (15)
 Hipparchus:
200-100 BCE,
Greek astronomer.
– Classified 1000+ objects by
brightness.
 1st
Class: Brightest objects.
 6th Class: Dimmest objects.
 System
used today is a
modified version called the
magnitude scale.
Magnitude
 Measures
the brightness of an object.
 Dimmer objects = larger number.
 Brighter objects = smaller number.
-26 Sun
-20.5 Milky Way Galaxy
-13 Full Moon
-4 Venus
-2 Jupiter
+1 Saturn
+2 stars of Big Dipper
+5 moons of Jupiter
+6 Uranus
+8 Neptune
+8 farthest you can see
with binoculars
+11 Prx. Cent.
+14 Pluto at its brightest
+30 Hubble Deep Space
Telescope
Types of Magnitude
Apparent
Magnitude:
–Brightness as seen from earth.
–Problem:
Distant
objects appear fainter.
Nearer objects appear brighter.
 Absolute
Magnitude:
–Brightness an object if it were
32.6 light years from earth.
(10
parsecs)
–Allows brightness to be
compared without differences in
distance.
–Problem: Need to know an
object’s distance from Earth.
Using apparent magnitude to find
absolute magnitude
β
Crucis (or Mimosa) has an apparent
magnitude of 1.25 and is 108 parsecs
distant. What is its absolute magnitude?
 M = m - 5 log(d/10)
 M = 1.25 - 5 log(108/10)
 M = 1.25 - 5 log(10.8)
 M = 1.25 - 5.x 1.0334
 M = 1.25 - 5.1671 therefore:
 M = -3.92
Why is Absolute Magnitude
important?
 Brightness
is directly related to
an object’s size and temperature.
Magnitude Venn Diagram (14)
Create a Venn Diagram comparing and
contrasting Apparent and Absolute
Magnitude.
 Draw a picture to illustrate the difference
between Apparent and Absolute Magnitude.
 Write a level 1 or 2 question and its
answer for each of the following ideas:

–
–
–
–
Hipparchus
Magnitude
Absolute Magnitude
Apparent Magnitude