Summer solstice is always on Tuesday

High temperatures, unpleasant weather make us feel like summer has arrived before. However, according to the astronomical calendar today June 21, Tuesday of the third week of June, which we call the summer solstice officially begins.

Summer solstice is what day?

Summer solstice is the day when the longest day of the year in the northern hemisphere is the day when the shortest daytime time is in the southern hemisphere. According to Western Astronomy, this day marks the beginning of summer in the northern hemisphere, and the beginning of the winter of the southern hemisphere. From the Eastern point of view, the Summer solstice is the mid-summer day , the Chi (至) in the Substitute (夏至) means the extreme point has been reached.On this day, the Sun will be at the highest point north in the midday sky, then slowly return to the south.

This year, the summer solstice officially started at 18h34 on June 20 (EDT), ie 5h34 on June 21 (Hanoi time).

On the summer solstice, the sunset is the longest in the year. (Photo: Meg-moir)

Why is the day of the solstice the longest day of the year?

When the Lice begins, the Earth leans 23.5 degrees above the Earth's axis . On June 21 (with years 20 - 6), the Arctic will face the Sun the most. Normally, winter solstice occurs when the upper half of the Arctic faces directly with the Sun and the South Pole is in darkness.

The Earth's northern hemisphere is most inclined to the Sun in the Summer Solstice.(Graphics: timeanddate.com. Translation: Ftvh.)

Tuesday is the day marking the highest point of the sun but not the highest temperature day because the temperature in the ocean begins to decrease. By mid-June, the Northern Hemisphere oceans still maintained the ' cool ' temperature since last winter.

Compared to the winter, in the summer, the Earth is farther away from the sun due to the elliptical Earth's orbit so there is a change in the distance from the Earth to the Sun. This gap is about three million miles (5 million kilometers) and makes the Earth's heat radiation 7% more than normal days.

If you are a person who likes to explore science, you will see that the summer solstice is the longest sunset in the year. At sunset, the temperature at the Sun's feet is about 12-18 degrees.

Lice take place twice a year, one in the summer is called Summer solstice in June, and the other in the winter is called the Winter solstice in December. North, Winter solstice day, the Sun is highest in the south.