Why does Canada have distinct summer and winter seasons?

When are tornadoes most likely to form and why? Why sun is bigger when rising or setting? Is sirius a star or planet? How does a reflecting telescope work to gather and focus light for astronomical observations? Is Sirius brighter than the evening star? Does the sun sit behind the moon? What was the physical description for Ben in Walk Two Moons? What are some risks of traveling into space? Who said The stars exist that you might know how high your dreams can soar? What space shuttle did john glenn travel in? What is the meaning of rainbow upon seeing in in the morning? A sentence with the word gaze? How often are Accuweather forecasts updated? Which direction does a space shuttle reenter earth? How does the Sun replenish its gases? What two processes caused the water droplets to form on the cover of a pan? Where did John Glenn lift off? Who was the first American to orbit the earth and what was the name of his spacecraft? What term specifically describes the process wherein the sun's radiation becomes trapped in the earth's atmosphere? How to locate the Milky Way in the night sky?