![]() →See your personalized Sun rise and set calculator. The amount of daylight each day will continue to increase until the summer solstice in June, during which the longest period of daylight occurs. On the March equinox, the Northern Hemisphere and Southern Hemisphere receive roughly equal amounts of sunlight neither hemisphere is tilted more toward or away from the Sun than the other.Īlthough in most locations (the North Pole and Equator being exceptions) the amount of daylight had been increasing each day after the winter solstice, after the spring equinox, many places will experience more daylight than darkness in each 24-hour day. Imagine standing on the equator the Sun would pass directly overhead on its way north. It’s called the “celestial” equator because it’s an imaginary line in the sky above the Earth’s equator. In the Northern Hemisphere, the spring equinox in the Northern Hemisphere (also called the March equinox or vernal equinox across the globe) occurs when the Sun crosses the celestial equator going south to north. Not quite as pleasant, but because Mars takes about two Earth years to orbit the sun, the seasons are twice as long.Winter Solstice 2023: The First Day of Winter ![]() Can you figure out which equinox goes where?īy the way, the red planet Mars, with a similar axial tilt, has seasons too. Halfway between winter and summer are the equinox points – spring and fall. These are the ‘winter’ and ‘summer’ points – the solstices. Stop at the points where the toothpick is tilted towards the bulb and where it points away from the bulb. Hold your tilted Earth about 15 cm away from the light bulb and orbit the lamp like the Earth orbits the sun – in a circle around the bulb. Tilt your Earth model so that the toothpick is about 23 degrees away from vertical. In this case, the grape represents Earth and the toothpick the Earth’s rotational axis. Poke the toothpick through the long axis of the grape. You’ll need a grape, a toothpick, and a light source like an unshaded lamp. You can actually simulate this cool feature of Earth’s orbit in your kitchen at home. In summer, we experience the greatest number of hours of daylight – up to 24 hours at the poles in winter, the fewest hours of daylight - no daylight at all at the poles! The first days of summer and winter are solstice days and, according to its definition, the sun has stopped - either gaining maximum height at noon in summer, or achieving minimum elevation at noon in winter. So where do the words "equinox" and "solstice" come from? Both come from the Latin - for "equal night" and "sun stand still." The first days of spring and fall are equinox days, when Earth experiences 12 hours of daylight and darkness. ![]() When the rotational axis is tilted away from the sun, the energy gain per square meter is lower. With the rays being closer to vertical, the energy gain per square meter of area is higher. ![]() Here’s the counter-intuitive part: Earth is closest to the sun in early January and most distant in early July! Turns out seasonal heating and cooling isn’t caused by how close we are to the sun, but instead is affected by the Earth's axis tiling toward or away from the sun. When the rotational axis is tilted toward the sun, the sun’s energy strikes that part of the planet at a steeper angle. These are the two extremes of annual solar illumination: longest days in the summer and shortest days in the winter. The winter Earth is tilted away from the sun the north pole deep in darkness around December 21. ![]() The summer Earth shows the north pole tilted towards the sun, bathed in sunlight, around June 20. To understand how the tilt causes seasons, look first at the summer and winter Earths. This image is waaaaay out of scale in almost every dimension shown (that’s another whole subject by itself!) but it does illustrate how the Earth’s daily spin axle is tilted away from vertical. ![]()
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