June 21 is going to be a long day. Do you know why?

Did you ever feel that the days leading up to the end of the summer feel longer and the nights shorter? It’s the “Solstice”. The Summer Solstice, in the northern hemisphere, falls roughly around June 21 or 22. Every year, this day is celebrated and several cultures mark the day according to their respective traditions.

What is Summer Solstice?

Solstice in Latin means ‘sun stand still’. The sun, during this time, reaches the highest position in the sky making it appear as if it is still.

Science behind this

Elementary level Science has taught us that the Earth revolves around the Sun and not the other way around as our ancestors believed. When the Earth revolves around the sun, it is also spinning on its own axis. This is what gives us night and day.

Let’s make it simpler — take a basketball as the sun and spin a top around it. The top is the Earth which goes around the basketball and also spins on its own.

As the axis of the Earth is tilted, it spins in a tilted position pointing to the North. During the summer, the North Pole tilts toward the Sun and the Sun’s rays fall on the north of the Equator — the imaginary line around the Earth separating the southern and northern hemisphere. During winter, it tilts away and the sun’s rays fall on the south of the Equator.

This is why during the summer, on June 21 every year, the summer solstice occurs giving us the longest day of the year. Of course, this happens in June if you’re living in the northern hemisphere. In the southern hemisphere, it’s the exact opposite — it happens in December.

Summer Solstice or Midsummer Day is a significant event in many cultures. In the olden days, many cultures welcomed the solstice by feasting, singing, dancing around and jumping over bonfires hoping for a good harvest. Even today, people celebrate Midsummer Day and follow different traditions and rituals with gusto.

Such traditions only give us a reason to celebrate. The solstice is celebrated world over because of its significance in astronomy and the changing seasons of the earth.

Trivia and facts to chew on

You must be aware of the prehistoric monument in England called Stonehenge. Apart from being known as an ancient burial ground, it has certain religious significance attached to it. Modern day druids gather at the towering structure on summer solstice and stay up till dawn to mark the occasion. In fact, in the last few years, people had gathered in thousands at the monument simply to “appreciate the solstice”.

In pagan traditions, certain ceremonial acts were observed on the day to appease gods for fertile land, favourable weather and good harvest. Rituals were also conducted to ward off evil and bring in prosperity.

Aztecs and Mayans built their temples and other structures aligned to the shadows cast by the sun and on this day, they too performed various rituals and ceremonial acts.

Summer sky or winter sky — it is the same just that during summer the stars appear fainter in the evenings and in winter a lot brighter, making us assume there are more stars this sea son. Then doesn’t the sky change at all? “It changes every minute!” says Nilesh Vayada, Astronomer and Astrophotographer, and secretary of the Amateur Astronomers’ Association, Mumbai. “This change is to do with earth’s rotation and not the movement of the stars or the planets.”

MADHUMITHA SRINIVASAN adds:

Movement

So, in keeping with the earth’s rotation, the sky “moves” two hours earlier every month. That is, a particular area of the sky that you spot at 10 p.m. in January can be spotted in the same spot in February at 8 p.m. Thus the sky as witnessed in January will appear to be different than the one in October or November.

One of the major astronomical events that we can look forward to in the coming months is the annual Perseids meteor shower which will peak on August 12. The Perseids shower is one of the best to observe, with upto 60 meteors falling per hour at the peak. However meteors are likely to be visible from July 23 to August 22.

With urbanisation having an impact on pretty much everything, is the sky also in any way affected? “Yes!” says Suhas B. Naik-Satam, Programme Coordinator (Scientific), Nehru Planetarium, Mumbai. “Light pollution, also called sky glow, is defined as light wastefully escaping into the night sky and causing a glow over urban/suburban areas. Sky glow is of particular irritation to astronomers, because it reduces contrast in the night sky to the extent where it may even become impossible to see the brightest stars.”

To keep an eye on the world beyond the earth’s atmosphere, log on to http://www.vigyanprasar.gov.in/news/sky.htm that tells you what constellations are positioned where in the sky to help you spot them easily. Google Sky gives you a peek into the universe by collating images from the Sloan Digital Sky Survey, the Digitized Sky Survey and the Hubble Space Telescope. You can Google for your favourite planets, constellation, stars, galaxies and more.

Here’s a fun activity you can take up that combines your creativity and astronomy: Pin the Star on the Sky: With eyes closed, place stars randomly on paper. Using these stars, create your own constellation and weave a story to go with it.

Throught the telescope

For those taking up amateur sky watching any good binoculars or telescope should do. Vayada gives some specifications: A telescope is of two types — lens and mirror telescope. A basic specification of these would be a 60 mm diameter for the lens telescope and 100 mm diameter for the mirror telescope. With this one can spot the rings around Saturn, Jupiter's four moons and the bright nebula.