Winter Solstice vs Summer Solstice
To understand the difference between summer and winter solstices, we need to have a clear understanding of the word solstice. We know that earth revolves around sun in an elliptical orbit, but it also spins around its own axis. This is an imaginary line going right across the planet from North Pole to South Pole. Fortunately for our planet, this axis is not perpendicular but tilted about 23.5 degrees and it is this tilt that gives us seasons on earth. This tilt makes one half of earth receive more direct rays from sun than the other half which remains away from earth.
The axis, when it tilts towards the sun, it makes northern hemisphere receive more direct rays from the sun than southern hemisphere. This phenomenon occurs between June and September and thus this is the period when it is summer season in the northern hemisphere. Again, this axis tilts away from the sun between December and March which is why we have winter season in the northern hemisphere during this period. While it is summers in northern hemisphere as it receives more direct rays from the sun, it is winter in the southern hemisphere, and vice versa in winters.
This event, that happens twice a year, is known as solstice. Though it is duration, in a broader sense, it can also be considered as beginning of a season in the two hemispheres. So, the day when the axis is such that it makes northern hemisphere start to receive more of sun’s direct rays is termed as summer solstice in the northern hemisphere (it is marked as winter solstice in southern hemisphere). Solstice is a word that comes from two Greek words sol (sun) and stitium (still). So during summer and winter solstices, sun appears to be still.
For nearly half of the year, (between March and September), northern hemisphere is inclined towards sun with maximum inclination around June 21. This is the day in northern hemisphere when we observe summer solstice while we observe winter solstice on December 21 when this inclination is least. So June 21, when it is summer solstice in the northern hemisphere, is the day when it is called winter solstice in the southern hemisphere. Conversely, on December 21, when it is winter solstice in the northern hemisphere, it is summer solstice in the southern hemisphere.
Difference Between Winter Solstice and Summer Solstice
• Rotation of earth around its own axis, which is tilted around 23.5 degrees to the perpendicular, causes seasons on earth.
• The period when this tilt is towards the sun is called summer solstice and the day on which this tilt is maximum is June 21 in the northern hemisphere. It is also called the longest day in the northern hemisphere.
• The period when this tilt is away the sun is winter solstice and the day on which this tilt is minimum is called winter solstice in the northern hemisphere. This day is December 21 which is also called the shortest day of the year.
• Summer solstice in northern hemisphere is called winter solstice in the southern hemisphere and winter solstice in northern hemisphere is called summer solstice in the southern hemisphere.