The solstice takes place on June 21 at 4:58 p.m. (peninsular time) and begins with a beautiful conjunction of Venus and Mars with the Moon. We offer you the 10 astronomical keys to the longest day of the year and the phenomena that will animate the sky during the summer period.
1. Start. Summer in the Northern Hemisphere (and winter in the South) will begin on June 21 at 4:58 p.m., official peninsular and Balearic time (3:58 p.m. in the Canary Islands).. But be careful, not every year summer begins on this same day in June; For example: in 2024 summer will start on the 20th. The variations from one year to another are due to the fit of the sequence of years of the Gregorian calendar (some are leap years and others are not) with the actual duration of an orbit of the Earth around the Sun.
2. Conjunction. The season begins with a beautiful conjunction of Venus, Mars and the Moon. To see it, you have to look to the west in the evening twilight, about two hours after the setting of the Sun, on June 21 or 22.. The Moon is these days like a fine bright edge (the new moon took place on the 18th) and we can take the opportunity to observe the beautiful ashen light on the darkened part of the lunar disk.
Conjunction of days 21 and 22
3. summer planets. Venus and Mars will continue to be visible in the evenings until they dip into the sun's glare as they approach the king star in late August.. Mercury will make a brief appearance between July and August. At dawn we will be able to continue observing Jupiter and Saturn, but the giant of the rings will disappear at the end of August, while Venus will then reappear at dawn in the east.
4. Three supermoons and one blue. The three full moons of the season will take place on July 3 and August 1 and 31.. During these three full moons our satellite will be in a position close to the closest possible to Earth (perigee), it is what is sometimes called a 'supermoon'. When a month has two full moons, the Anglo-Saxons call the second one a 'blue moon' (the fourth full moon of a season that has four is also called a 'blue moon'). So the full moon on August 31 will be a 'blue moon', but of course this has nothing to do with the color of the Moon.
5. Aphelion. The paradoxical circumstance occurs that summer in the Northern Hemisphere arrives when the Earth, in its elliptical movement around the Sun, is as far away as possible from the star king.. The furthest point, called aphelion, will be reached on July 6, when the Earth is about 152 million kilometers from the Sun, that is, 5 million kilometers further than the perihelion position we passed through on July 4. from January.
6. Sin eclipses. This summer does not bring us any eclipse, neither of the sun nor of the moon. We will have to wait until October to be able to witness a partial solar eclipse and a penumbral lunar eclipse.
7. Tears of Saint Lawrence. This is a good year to observe the Perseids, the most important meteor shower of the summer. This is because the maximum activity of the rain, on August 12, will take place with the waning moon (the new moon will be on the 16th).. Observation conditions are much less favorable for the Delta Aquarids, which have their maximum on July 30, very close to the full moon on August 1.
solstices and equinoxes
8. The longest day. The shortest boreal night takes place on the day of the summer solstice. On that day, in Madrid the night will last 8 hours and 57 minutes, while there will be 15 hours and 3 minutes of sunlight. Oddly enough, the longest day of the year is not the day the Sun rises the earliest, nor is it the day the Sun sets the latest. This is because the Earth's orbit is an ellipse and the axis of this ellipse is not related to the inclination of the Earth's axis that defines the seasons. The earliest sunrise occurred on June 14, while the latest sunset will occur on June 27.
9. Tropic of Cancer. At the summer solstice, the Earth's North Pole is closer to the Sun than the South Pole. Seen from Earth, the Sun is at noon at the “Tropic of Cancer”, its northernmost possible position.
10. 93 days and 15 hours. Summer will last 93 days and 15 hours. It will end on September 23, 2023 with the arrival of autumn. In fact, summer is always the longest season of the four. This is due to Kepler's Second Law: the line that joins the Earth to the Sun sweeps out equal areas in equal times. Because the Earth is now in its positions furthest away from the Sun (aphelion), it is moving with less speed, which translates into a longer duration of summer compared to the other three seasons.
Rafael Bachiller is director of the National Astronomical Observatory (National Geographic Institute) and academic of the Royal Academy of Doctors of Spain.