Latitude and Longitude

1
Latitude and Longitude

• An Overview

2
Changing Perspectives

• People normally see the world from the
  perspective of standing on the surface of the
  earth
• To understand latitude and longitude, you are
  required to change your perspective or frame of
  reference

3
Changing Perspectives Contd

• You must now see the earth from a position in
  space looking down at the world, just like an
  astronaut!
• The same applies to the sun, which is a sphere
  just like earth.
• This can be challenging, but it can be done!

4
The Equator
Latitude is measured above and below the Equator
in degrees.
http//nationalatlas.gov/articles/mapping/a_latlon
g.htmlthree
5
Lines of Latitude
These parallel lines on the globe are lines of
latitude.
http//plantwatch.sunsite.ualberta.ca/library/imag
es/lat.jpg
6
Latitude
Latitude angles are measured from the centre of
the earth (vertex of the angle)
http//www.csmate.colostate.edu/cltw/cohortpages/v
iney/latitude.html
7
Prime Meridian
The Prime Meridian passes through Greenwich,
England
http//www.mrsciguy.com/sciimages/longitude1.jpg
8
Prime Meridian Marker
A marker showing the actual location of the Prime
Meridian in Greenwich, England
http//www.cavinguk.co.uk/holidays/London2006/norm
al/PrimeMeridian.jpg
9
Lines of Longitude
http//plantwatch.sunsite.ualberta.ca/library/imag
es/long.jpg
10
Longitude Angles

• Longitude is measured in degrees east or west of
  the Prime Meridian
• Angles are measured from the centre of the earth
  (vertex of angle) east or west of the Prime
  Meridian

http//www.csmate.colostate.edu/cltw/cohortpages/v
iney/latitude.html
11
Longitude

• Top down view of world
• Longitude is measured in degrees east or west of
  the Prime Meridian

http//nationalatlas.gov/articles/mapping/a_latlon
g.htmlthree
12
Latitude and Longitude combined
Latitude and longitude measurements are based on
angle measurements as shown in this diagram and
previous two diagrams
http//cache.eb.com/eb/image?id64904rendTypeId4
13
What is the Lat and Long of this point?
http//www.digitalgeography.co.uk/wp-content/uploa
ds/2007/07/grid.jpg
14
How to Measure Sunspot Movement with Angles

• Problem We need to measure the change in
  longitude of the sunspots on a 2-D image of the
  sun
• Solution The next few slides show you how to do
  this.

15
How to Measure Sunspot Movement with Angles

• 1st draw a line straight up to the edge of the
  sun and mark the point

NASA/SOHO
16
How to Measure Sunspot Movement with Angles Contd

• 2nd on a more recent image, repeat step 1

X
NASA/SOHO
17
How to Measure Sunspot Movement with Angles Contd

• 3rd locate the centre of the sun and draw an
  equator
• The cross lines found the centre

X
NASA/SOHO
18
How to Measure Sunspot Movement with Angles Contd

• 4th draw lines from the centre to the marked
  points and measure the angle with a protractor

X
NASA/SOHO
19
How to Measure Sunspot Movement with Angles Contd

• The angle measured represents the change in
  longitude of the sunspot

X
NASA/SOHO