Here's what you might be asking:
* When does the sun shine directly *on* Earth? This happens when the sun's rays are hitting a particular spot on Earth at a 90-degree angle. This happens at the equator during the equinoxes, which occur around March 20th and September 23rd.
* When does the sun shine directly *on* a specific location on Earth? This depends on the latitude of the location. For example, in the Northern Hemisphere, the sun shines most directly on the Tropic of Cancer (around 23.5° North) during the summer solstice (around June 21st). In the Southern Hemisphere, it shines most directly on the Tropic of Capricorn (around 23.5° South) during the winter solstice (around December 21st).
It's important to remember that the Earth is tilted on its axis, and this tilt is what causes the seasons.
