![Tree through the four seasons](/sites/default/files/styles/resource_card_image_360x300_/public/2019-09/Tree_through_the_four_seasons.jpg?itok=d1-felZQ)
Why do we have seasons?
Backgrounders
Learn why seasons change. Discover how they’re different in the Northern and Southern hemispheres.
![Adult and children looking through telescope](/sites/default/files/styles/resource_card_image_360x300_/public/2019-09/adult_and_children_looking_through_telescope.jpg?itok=eKeL_YGd)
The Optics of Telescopes
Backgrounders
Learn about telescopes, how they work & why they're important to astronomers.
![Why is everything so small down there?](/sites/default/files/2019-08/why-is-everything-so-small-down-there.jpg)
Why is everything so small down there?
Hands-on Activities
Explore how we see things far and near and from different angles. It's all about perspective!
![ChaoticMind75 - iStock](/sites/default/files/2019-08/why-is-it-colder-in-the-winter-even-though.jpg)
Why is it colder in the winter even though the Earth is closer to the Sun?
Hands-on Activities
Learn why we have seasons in this hands on activity.
![The planet Mars](/sites/default/files/2019-10/Mars.png)
What is your weight on another planet?
Hands-on Activities
Do you weigh the same on Jupiter as you do on Earth? Learn to calculate your weight on a different planet.
![What would happen if a meteor hit Earth?](/sites/default/files/2019-08/what-would-happen-if-a-meteor-hit-the-earth_0.jpg)
What would happen if a meteor hit Earth?
Hands-on Activities
Explore the effects of asteroid impacts in this hands on activity.
![The Parkes Observatory in New South Wales, Australia](/sites/default/files/styles/resource_card_image_360x300_/public/2019-10/Park_Observatory_NSW_Australia.jpg?itok=K11hu9qK)
The Search for Extraterrestrial Intelligence - and How You Can Help!
STEM Explained
When astronomers search for extraterrestrial life, they often have to listen for radio waves coming from deep space. If you’re interested, you can help!
![International Space Station in the rays of the Sun](/sites/default/files/styles/resource_card_image_360x300_/public/2019-09/international-space-station-in-the-rays-of-sun.jpg?itok=XvahdQ2K)
Temperature on Earth and on the ISS
Backgrounders
Temperature is an important part of life on Earth and life in space. This backgrounder explains what temperature is, how it affects people and how it is controlled on the International Space Station.
![Mars Science Laboratory Parachute Qualification Testing](/sites/default/files/styles/resource_card_image_360x300_/public/2019-09/Mars_science_lab_parachute_testing.jpg?itok=Ly8xx3i5)
Testing Parachutes for Mars
STEM Explained
NASA engineers apply kinematics and dynamics to test parachutes designed specifically to help space probes land safely using aerodynamics.
![The rocky planets](/sites/default/files/styles/resource_card_image_360x300_/public/2019-11/Rocky_planets.jpg?itok=5IsUrgOh)
The Inner Solar System
STEM Explained
Earth is covered in rocks. So are Mercury, Venus, Mars and the Moon. Does that mean the rocky planets are all the same?
![Space junk](/sites/default/files/styles/resource_card_image_360x300_/public/2019-10/space-junk-orbiting-earth.jpg?itok=nA6-Kgmi)
Space Junk
STEM Explained
Litter isn't just a problem on Earth. When litter ends up in space, it can cause collisions and other consequences for satellites, the International Space Station and even for people on Earth!
![Former Canadian astronaut Robert Thirsk enjoys cycling on board the ISS](/sites/default/files/styles/resource_card_image_360x300_/public/2019-09/Robert_Thirsk_cycling_on_ISS.jpg?itok=YDleE__K)
Spaceflight and Bone Loss
STEM Explained
Astronauts can experience bone loss in space. To understand why, you need to know a bit about how bones are formed and maintained in your body.
![Sunrise Sunrise](/sites/default/files/styles/resource_card_image_360x300_/public/Perth_sunrise.jpg?itok=zGCNcEx1)
Sun: Sunrise
Picture Collections
5 images of scenes showing various sunrises
![Radiation shielding garment on the International Space Station](/sites/default/files/styles/resource_card_image_360x300_/public/2020-02/ISS_radiation_shield_garment.jpg?itok=iWfQ6aCb)
Radiation and Human Space Exploration
STEM Explained
One of the greatest hazards that humans in space face is cosmic radiation. Learn what cosmic radiation is, why it's dangerous, and ways that we are looking at protecting humans in deep space.