Grade by Grade
E. Earth and Space Systems · Space

Satellites Watching Our Changing Earth

E1.2 A3.2 A1.1About 45 minutes
Learning goals
  • I can explain how satellites observe Earth from space.
  • I can give examples of how satellite data helps us understand environmental changes, including climate change.
  • I can assess what satellites do well and what they can't do on their own.
  • I can explain how satellite data is combined with math, geography and local knowledge.

Words to know

Earth observation
Studying Earth from above, often with satellites.
data
Facts and measurements collected to answer questions.
radar
A technology that sends out radio waves and measures the echoes. It works through clouds and in the dark.
climate change
A long-term change in Earth's usual weather patterns, such as average temperatures rising over many years.
ozone layer
A layer of gas high in the atmosphere that blocks much of the Sun's harmful ultraviolet light.
sea ice
Frozen ocean water. In the Arctic, people use it for travel and hunting.

Remember from Grade 5

In Grade 5 you learned that burning fossil fuels adds carbon dioxide to the atmosphere and contributes to climate change. But how do scientists know that the planet is changing? One of their most powerful tools is in orbit.

A view from above

From the ground, you can see only the area around you. A satellite can see huge regions at once, and it passes over the same places again and again for years. Comparing pictures and measurements from different years shows what is changing.

Satellites carry different tools:

  • Cameras take pictures in visible light, like a giant camera in the sky.
  • Infrared sensors measure heat, for example the temperature of the sea surface or a wildfire.
  • Radar sends out radio waves and measures the echoes. Radar can "see" through clouds and in the dark, which matters in the Arctic winter, when it is dark for weeks.
  • Other instruments measure gases in the air.
satelliteorbitEarth
A satellite orbits Earth and points its instruments at the surface, passing over the same places again and again. Not to scale.

Satellites and our changing planet

  • Ice: Canada's RADARSAT Constellation Mission, three identical satellites launched on June 12, 2019, monitors Canada's environment, oceans and ice, and helps emergency teams during natural disasters.
  • The ozone layer: Canada's SCISAT satellite measures many gases high in the atmosphere, including substances that harm the ozone layer (the Canadian Space Agency says it measures more of them than any other satellite), with a focus on changes over Canada and the Arctic.
  • Ice sheets: NASA's GRACE satellites measured changes in Earth's gravity to show that Greenland's ice sheet has been losing ice.
  • Snow: satellite observations show that the amount of spring snow cover in the Northern Hemisphere has decreased.
  • Weather and wildfires: weather satellites track storms and smoke so forecasters can warn people.

NASA says that Earth-orbiting satellites have helped scientists see the big picture of climate change.

What satellites can't do alone (assessing the role)

Satellites are powerful, but they are not the whole answer.

  • They need ground checks. Measurements from space are compared with measurements taken on the ground, on ships and on the ice.
  • They need people to interpret the data. Numbers and pictures mean something only when scientists study the patterns.
  • Local knowledge matters. In Nain, Nunatsiavut (Labrador), SmartICE, a social enterprise that works with Indigenous communities, trains Inuit youth to build and operate sea ice sensors. Some sensors are frozen into the ice; another is pulled behind a snowmobile. Their measurements are combined with local observations, like the locations of cracks and seal holes, and with Inuit knowledge, to make sea-ice travel maps. Warming has made the ice less predictable, so this information helps people travel and hunt more safely.
  • They cost a lot to build and launch, and they stop working one day.

Using other subjects (A3.2)

Understanding satellite data needs math (graphs, averages, comparing numbers over time), geography (maps and locations), coding (sorting huge amounts of data), and communication (sharing what we learn so people can act).

Worked example

Let's read a pattern in data

Here is practice data (made-up numbers, but they behave like real ice data) for the area of sea ice in one bay at the end of summer.

2000: 50 km² · 2005: 46 km² · 2010: 41 km² · 2015: 38 km² · 2020: 33 km²

What is the pattern? What could it mean? What else would you want to know?

  1. Find the trend: the numbers get smaller every 5 years. The ice area is decreasing.
  2. Calculate the change: 50 − 33 = 17 km² less ice over 20 years.
  3. Possible meaning: warmer temperatures could be melting more ice each summer, which matches what scientists expect with climate change.
  4. Assess the evidence: five numbers from one bay are not enough to be sure. We would want more years, more places, ground checks, and the knowledge of people who live there and travel on the ice.

The ice area decreased by 17 km² over 20 years. That is a pattern that could be linked to warming, but scientists would check more data and local observations before drawing a conclusion.

Sea ice in one bay at the end of summer (PRACTICE data)0204060km²502000462005412010382015332020year
The practice data from the example as a line graph. The line slopes down from 50 km² to 33 km²: a decreasing trend. Remember these numbers are made up for practice.
Just for fun

Never play hide-and-seek with a radar satellite. Hiding under the clouds won't work, and waiting until dark won't help either: radar can "see" through both! 🛰️

Hands-on activity

Be a satellite for a week

You need: a notebook, a pencil, a window or a safe outdoor spot, and a device to look at a weather website (with a grown-up).

  1. Observe from the ground: each day at the same time, record the temperature (from a thermometer or forecast), the cloud cover (none, some, lots) and any precipitation.
  2. Observe from space (A1.1): with a grown-up, look at the satellite image on Environment and Climate Change Canada's weather website or another weather site for your area at the same time. Is your area cloudy in the satellite image?
  3. Compare: did the satellite image match what you saw from the ground?
  4. Research (A1.1): find one more way satellites are used to watch Canada's environment (ice, forests, wildfires, floods or crops). Write down your source.
  5. Connect (A3.2): make a bar graph of the daily temperatures you recorded.

What to look for: satellite images usually match ground observations for clouds, but the ground view tells you details the satellite can't (like how it felt, or if it drizzled lightly). This is why scientists combine both. Good sources include the Canadian Space Agency, Environment and Climate Change Canada and NASA.

Safety: never look at the Sun when observing the sky. Use the Internet with a grown-up.

Your turn

1

Why are satellites good at noticing changes on Earth?

2

What can radar satellites do that ordinary cameras can't?

3

What does Canada's RADARSAT Constellation Mission monitor?

4

What does SCISAT study?

5

Name one change from climate change that satellites have measured.

6

Why do scientists still need measurements from the ground?

More practice: warm-up

1

What is Earth observation?

2

What is data?

3

How many satellites are in the RADARSAT Constellation Mission?

4

What does the ozone layer do?

5

Name one subject besides science that helps us understand satellite data.

More practice: on your own

1

Why is radar especially useful for watching Arctic ice in winter?

2

How does SmartICE combine technology and Inuit knowledge?

3

A satellite shows a forest area is smaller than 10 years ago. Give two questions a scientist should ask before deciding why.

4

Why might weather satellites save lives?

5

Using the practice data (2000: 50 km², 2020: 33 km²), what was the average decrease per year?

Challenge

1

Assess this statement: "Satellites are all we need to understand climate change." Do you agree? Give reasons on both sides.

2

Why do you think Inuit youth operating the ice sensors helps communities trust the data?

3

Explain how math helps turn satellite pictures into evidence of change.

Check your understanding

Quiz

1.

Why can satellites show changes over time?

2.

Which technology can see through clouds and in the dark?

3.

Canada's SCISAT satellite studies...

4.

Satellite observations show that spring snow cover in the Northern Hemisphere has...

5.

Why do scientists combine satellite data with ground observations?

6.

SmartICE, in Nain, Nunatsiavut, combines ice sensors with...

For parents and teachers

Big idea (E1.2): assess the role of space technology in observing and understanding environmental changes on Earth, including climate change. Students weigh strengths and limits. The lesson connects science with math, geography and coding (A3.2) and practises research (A1.1).

How to help: look at the satellite map on Environment and Climate Change Canada's weather site together. Ask: "What can this picture tell us? What can't it tell us?"

Common difficulties:

  • Thinking satellite data is perfect. It needs checking and interpreting.
  • Treating practice data as real. The sea-ice numbers in the example are invented for practice; say so if your child quotes them.
  • Presenting Inuit knowledge as old-fashioned. SmartICE shows Inuit youth using and building new technology today.

Sources: Canadian Space Agency (RADARSAT Constellation Mission, SCISAT); NASA Climate "Evidence" page (GRACE and Greenland, Northern Hemisphere spring snow cover); Atlantic Canada Opportunities Agency article on SmartICE.