What is the summer solstice?
What is the summer solstice ? Summer has officially arrived in the northern hemisphere on June 21st, marking the longest day and the shortest night.
The solstice precisely happened at 11:54am EDT, when the Sun reaches the point that is the farthest north on what we call the celestial equator. In reality, that’s the day of the year where the Sun rises and sets the closest to due North. For an observer on the Tropic of Cancer, the Sun will appear right at Zenith. However for an observer at midnorthern latitudes, the Sun never appears right overhead, but the course of the Sun in the sky will reach its highest and its longest.
The solstice corresponds to the longest day of the year and the shortest night. However that doesn’t mean we can stargaze all night either. You still need to count the twilight times. Since the Sun describes its flattest course of the year below the horizon (and above for those north of the Arctic circle), the twilight times (Civil, nautical, astronomical) will also be elongated. If you live above 53° North of latitude, you don’t even get a fully dark night time either and you remain stuck in the astronomical twilight for a few hours before sunrise again. On a side note, the earliest sunrise and the latestest sunset do not coincide with the summer solstice. The former occurred on June 14thwhile the latter does not come until June 27th.
Local midnight in Denmark on June 21stat solstice. That’s the brightest point of the night at these latitudes!
Interestingly enough, many people think the summer solcistce is the time of the year where the Sun is at its closest to the Sun, probably because of the warmth of our Northern Hemisphere summers. However it’s quite the opposite. On July 4, at 6:11 p.m. EDT (2211 GMT), we’ll be at the point in our orbit farthest from the sun (called aphelion), a distance of 94,513,221 miles (152,104,285 km). Conversely, back on Jan. 3, Earth was at perihelion, the point in its orbit closest to the sun. The difference in distance between these two extremes measures 3,109,667 miles (5,004,524 km), or 3.3% of the average distance between the sun and Earth. That small change leads to a difference of nearly 7% in the radiant heat received by the Earth.
Theoretically, for the Northern Hemisphere, the difference in the distance to the sun tends to warm our winters and cool our summers. But in reality, the preponderance of large land masses in the Northern Hemisphere outweighs this effect, making our winters colder and summers hotter than those of the Southern Hemisphere.
From now on, the days will progressively get shorter and the nights longer again, until December 22nd. However until the second half of the summer (After August 1st), these effects will not be very noticeable unless you are at high latitudes. So before the dark hours of the winter, you’ll still have plenty of time to enjoy the warms days of summer!
What is the summer solstice ? – Could you live like this ?