45 Questions
What is latitude?
The angle that describes the north-south position
Where is the Prime Meridian located?
Royal Observatory at Greenwich in London, England
What is a parallel on the Earth's surface?
A circle connecting all locations at a given latitude
How can the Earth's shape be mathematically defined?
By using a sphere representation assuming the earth is perfectly round
What is the accuracy range of phone GPS?
3-15 meters
What does GNSS consist of?
Space, Control, and User segments
In which year did the first space images get captured from unmanned rockets?
1948
When did remote sensing begin?
1960
Which of the following is an Earth observation system?
WorldView
What are the Canadian innovations in Earth observation mentioned in the text?
CanadARM and RADARSAT constellation
What does Urthecast provide?
High-resolution video of the Earth from the International Space Station
What is wavelength?
The distance between wave peaks
What is the most important vegetation pigment mentioned in the text?
Chlorophyll
What does NDVI stand for?
Normalized Difference Vegetation Index
What is the smallest unit of distance that can be determined by a sensor measurement of the target?
Spatial resolution
Why would Canada want its own receiving station for satellite data?
To receive data in real-time from polar orbiting satellites for various purposes
Approximately how long does the Landsat record go back (years or decades)?
50 years
What are the most recent Landsat satellites?
Landsat 7, 8, and 9
What are the three components of spectral resolution?
The number of spectral channels/bands used, their location in the electromagnetic spectrum, and the bandwidth of each channel/band
What happens to near infrared photons when they intercept healthy vegetation?
They are highly reflected by chlorophyll, so with healthy vegetation, they will be reflected more than unhealthy vegetation
Name and generally describe the sensor bands on a satellite with sub-metre spatial resolution. Name three things this satellite is best suited to observe.
Visible and NIR spectrums, good for observing detailed satellite imagery for military use, monitoring buildings, urban infrastructure, and trees
What is the minimum number of visible satellites needed for accurate positional location using GNSS?
4
Which orbit is best suited for weather monitoring due to its consistent coverage of the same areas?
Geostationary orbit
In which orbit are most remote sensing satellites located for predictable path and simultaneous measurements?
Close Elliptical orbit
What does GNSS stand for?
Global Navigation Satellite Systems
Which type of orbit is used for GPS tracking due to its remote location?
Far Elliptical orbit
What is the altitude range for a geostationary orbit?
Above 35,786 km
Which method is NOT used for space junk collection?
Space elevator
Which layer of Earth's atmosphere has the lowest air molecules?
Thermosphere
What is the primary use of geostationary orbits?
Weather monitoring
Which satellite system is NOT part of GNSS?
ISRO
What is the best orbit for space travel due to its proximity and gravity effect?
Low-Earth orbit
Which type of orbit is used for telecommunications and satellite TV satellites?
Geostationary orbit
Which map projection distorts the size of countries, making Greenland appear similar in size to Africa?
Mercator projection
What was the meter originally defined as in 1793?
One ten millionth of the distance from the equator to the north pole
How many nanometers (nm) are equal to one micrometer (µm)?
1000 nm
Which type of map covers a large area with coarse detail?
Small scale map
How is scale indicated on a map?
Bar scale or fractional/ratio scale
What is the purpose of geodetic markers?
Establishing relative and absolute positions for triangulation
Which type of positioning is represented by coordinates of a point in space?
Absolute positioning
What is latitude easier to calculate in?
Ocean navigation
What do conformal map projections preserve?
Angles
What is the only correct representation of the Earth's surface?
Geoid
What is the current definition of the meter based on?
The speed of light
What is the appropriate map scale for a neighborhood?
1:15,000
Study Notes
Earth Representation and Measurement
- The Earth can be represented using three methods: sphere, ellipsoid, and geoid, with the geoid being the only correct representation of the Earth's surface.
- Equivalent projections preserve area but distort shape, while conformal projections preserve angles but distort size.
- The Mercator projection distorts the size of countries, making Greenland appear similar in size to Africa when it is actually 1/14th the area.
- The meter was first defined in 1793 as "one ten millionth of the distance from the equator to the north pole," and is now defined based on the speed of light.
- One micrometer (1 µm) equals 1000 nm.
- Small scale maps cover a large area with coarse detail, while large scale maps cover a small area with great detail.
- Scale can be indicated on a map using a bar scale or a fractional/ratio scale.
- Appropriate map scales for different areas range from 1:40,000,000 for worldwide to 1:15,000 for a neighborhood.
- Devices for measuring distances include electron microscopes, optical microscopes, cameras, and telescopes.
- Relative positioning is determining a location relative to other landmarks, while absolute positioning is represented by coordinates of a point in space.
- Geodetic markers are points with accurately established relative and absolute positions, forming a network used for triangulation.
- Latitude is easier to calculate in ocean navigation, while longitude requires a precise clock for accuracy.
Test your knowledge of Earth representation and measurement with this quiz. Explore different map projections, scales, distance measurement devices, and positioning methods. Learn about the geoid, ellipsoid, and sphere as Earth representations, and understand the importance of accurate positioning and scale in maps.
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