Summer
The start of summer
The summer of 2024 in the northern hemisphere will begin on 20 June at 22:51 hours Spanish mainland time according to calculations by the National Astronomical Observatory (National Geographic Institute - Ministry of Transport and Sustainable Mobility). This season will last approximately 93 days and 16 hours, and will end on 22 September with the beginning of autumn.
The beginning of summer in the northern hemisphere is defined by the moment when the Earth passes through the point in its orbit from which the Sun has its maximum northern declination. On the day when this happens, the Sun reaches its highest elevation above the horizon at noon and describes the longest arc in the sky. As a result, this is the day with the most hours of sunlight of the year. In addition, for several days the maximum height of the Sun at noon does not seem to change, and because of this, the beginning of summer is also called the summer solstice (from the Latin solstitium, still Sun).
The beginning of summer in the northern hemisphere coincides with the beginning of winter in the southern hemisphere.
The sky during summer 2024
Summer nights, although short, are usually the warmest of the year, and therefore represent a good opportunity to explore the sky. In addition, in summer it is common to travel to places such as the countryside and the beach, where dark skies allow us to see the sky better.
The sky after sunset in early summer will not have any planets visible. Mercury will make a brief appearance only for a few weeks during July. From August onwards, Venus will appear low on the horizon. We will have to wait until early September to see Saturn rising in the east at dusk.
On the other hand, the sky before sunrise , will begin the season with three planets visible: Mars, Jupiter and Saturn, but the second will disappear in the glow of dawn in mid-September. At the end of summer Mercury will become visible at dawn.
In addition to the planets, it is easy to distinguish groups of bright stars in the sky. The most characteristic of summer is the triangle formed by Altair, in the constellation of the Eagle, Deneb, in the constellation of the Swan and Vega, in the constellation of the Lyre. This is the so-called summer triangle, and is technically speaking an asterism, as it combines stars from different constellations. To the south, typical of summer are the constellations Scorpius, with the bright reddish star Antares, and Sagittarius, whose position roughly indicates the centre of the Milky Way. This white band, representing the combined brightness of the millions of stars that make up our galaxy, can be seen in summer in all its splendour across the sky from south to north, although a dark sky is necessary to distinguish it well.
Other phenomena of astronomical interest during the summer of 2024 will be the Delta Aquarid meteor showers, expected to peak around 31 July, and the popular Perseids, expected to peak around 12 August. The full moons of the season will occur on 22 June, 21 July, 19 August and 18 September.
On 5 July July there will be the moment of maximum annual distance between the Earth and the Sun, known as aphelion. When that happens, our distance from the Sun will be just over 152 million km, which is about 5 million km more than at the time of the smallest distance (perihelion), which happened on 3 January.
During the autumn of 2024, one partial lunar eclipse will occur on 18 September, and will be visible in America, Europe, Africa. The phase of partiality (visible in Spain) will begin at 4:13 Spanish mainland time and will end at 5:16.
Some interesting facts about summer
With just over 93 days, summer in the northern hemisphere is the longest season of the year. This is because the Earth's orbit around the Sun is not circular but elliptical and summer coincides with the time of year when the Earth is furthest from the Sun. When this happens, the Earth moves more slowly in its orbit (according to what is known as Kepler's second law), and therefore needs more time to reach the point where the next season begins, which is autumn.
The beginning of summer can occur on at most three different dates in the calendar (20-22 June). Throughout the 21st century, summer will begin on 20 and 21 June (the official Spanish date), with the earliest beginning in 2096 and the latest in 2003. The variations from year to year are due to the way the sequence of calendar years (some leap years, some not) fits in with the length of each orbit of the Earth around the Sun.
Although the day of the summer solstice corresponds to the day with the highest number of hours of sunlight, the difference in hours between day and night depends on the latitude of the place. For the latitude of Madrid, the day of the summer solstice will have 15 hours and 3 minutes of sunlight, compared to 9 hours and 17 minutes of sunlight on the shortest day (winter solstice). The difference between the longest and shortest day is therefore almost six hours. As we get closer to the equator, this difference decreases, while at the Earth's poles the difference is at its maximum.
For more information on the astronomical phenomena of the year, please consult the Almanak of the Astronomical Observatory, published by the National Geographic Institute.
Information provided by the National Astronomical Observatory (IGN, Ministry of Transport, Mobility and Urban Agenda). Reproduction in whole or in part is authorised provided the source is acknowledged.