Summer Solstice 2020: Here's why today (June 21) will be the longest day of the year
The summer solstice, also known as estival solstice or midsummer, marks the official start of summer. It brings the longest day and shortest night of the year for the 88 percent of Earth's people who live in the Northern Hemisphere. The Summer season solstice falls during June solstice in the northern hemisphere. Summer solstice occurs when one of the Earth's poles has its maximum tilt toward the Sun. It happens twice yearly, once in each hemisphere (Northern and Southern). Earth will be hosting annular solar eclipse and summer solstice, or the first day of summer today, June 21.
Also, today (June 21) is the longest day of the year, when we will get to witness a celestial event known as the ‘Ring of Fire’ solar eclipse or annular solar eclipse. People in India will get to witness another annular solar eclipse on Sunday (today) after the one which occurred in India and world in December (2019) last year.
Summer solstice in the Northern Hemisphere
Earth has a slight tilt as it orbits the Sun, and June is one of two times each year when that tilt is most prominent: a solstice. At the solstices, which happen each year in June and December, Earth’s tilt is at the greatest angle with respect to the plane of its orbit, meaning that one hemisphere is tilted towards the Sun, and the other hemisphere is tilted away.
In both hemispheres, the Sun will rise and set at its northernmost point on the horizon. After June 20, the Sun will appear to travel south.
The Science Behind the Summer Solstice
The Science Behind the Summer Solstice
Today, June 21 is the summer solstice in the northern hemisphere. But what causes this change in seasons? And what exactly is a solstice? It’s all about Earth’s tilt!
Many people believe that Earth is closer to the Sun in the summer and that is why it is hotter. And, likewise, they think Earth is farthest from the Sun in the winter.
Although this idea makes sense, it is incorrect. There is a different reason for Earth’s seasons.
Earth’s axis is an imaginary pole going right through the center of Earth from “top” to “bottom.” Earth spins around this pole, making one complete turn each day. That is why we have day and night, and why every part of Earth’s surface gets some of each.
This view from our Earth Polychromatic Imaging Camera on the National Oceanic and Atmospheric Administration's DSCOVR satellite shows the change in Earth’s tilt between the June and December solstices.
To mark the beginning of summer, here are four ways to enjoy the many wonders of space throughout the season:
1. Spot the International Space Station
As the third brightest object in the sky, the International Space Station is easy to see if you know when to look up. Sign up to get alerts when the station is overhead:
2. Treat your ears to space-related podcasts
From our “Gravity Assist” podcast that takes you on a journey through the solar system (including the Sun!) to our “NASA in Silicon Valley” podcast that provides an in-depth look at people who push the boundaries of innovation, we have podcast offerings that will suit everyone’s taste.
3. Explore space by downloading NASA apps
Our apps for smartphones, tablets and digital media players showcase a huge collection of space-related content, including images, videos on-demand, NASA Television, mission information, feature stories, satellite tracking and much more.
