--- title: What Is the Summer Solstice? 4 Facts You Should Know description: The 2018 summer solstice, the longest day of the year, starts on June 21. Here's what you need to know, including what time it starts canonical: https://time.com/5314789/summer-solstice-facts/ author: Gina Martinez article:opinion: false article:content_tier: free article:published_time: 2018-06-21T09:00:43.000Z article:modified_time: 2026-10-12T09:31:41.320Z article:section: Science og:title: Today Is the Longest Day of the Year. Here's What to Know About the 2018 Summer Solstice og:description: There are 17 hours of sunlight og:url: https://time.com/5314789/summer-solstice-facts/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltfa3a16e10fddbf7c/6989336a97cdff49e36b5899/summer-solstice-2018-facts.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 4816 og:image:height: 2709 og:image:alt: Summer solstice at Stonehenge og:type: article twitter:card: summary_large_image twitter:title: Today Is the Longest Day of the Year. Here's What to Know About the 2018 Summer Solstice twitter:description: There are 17 hours of sunlight twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltfa3a16e10fddbf7c/6989336a97cdff49e36b5899/summer-solstice-2018-facts.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # Today Is the Longest Day of the Year. Here's What to Know About the 2018 Summer Solstice > Sponsored content. 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Future Proof is free at time.com/newsletters. ### Sources * TIME Newsletters: [time.com/newsletters](/c/time-nl-futureproof-2026q3/newsletters?i=47d11d31-43cc-4bfd-8a5c-811d796eef93&cr=time-nl-futureproof-2026q3-v1) ## Video: What to Know About the Longest Day of the Year [Watch (HLS stream): What to Know About the Longest Day of the Year](https://cdn.jwplayer.com/manifests/hcrZvI2T.m3u8) (2:31)  _Published 2018-06-20. Your guide to the summer solstice._ by [Gina Martinez](https://time.com/author/gina-martinez/) ## Gina Martinez Jun 21, 2018 9:00 AM UTC by [Gina Martinez](https://time.com/author/gina-martinez/) ## Gina Martinez Jun 21, 2018 9:00 AM UTC While it’s already been hot for weeks, summer doesn’t officially start until the [summer solstice](http://time.com/3928453/summer-solstice-2015/), which falls on Thursday, June 21 this year. The summer solstice, which is the longest day of the year, officially starts Thursday morning in the Northern Hemisphere. During the summer solstice, the sun appears to stand still as it reaches its highest point, before moving off toward the horizon. Here’s everything you need to know about the 2018 summer solstice, including what it means and how Stonehenge is connected to the annual event. ## What is the summer solstice? While the calendar may say June 1 was the first day of summer, the season actually starts [when the summer solstice happens](http://time.com/4825634/summer-solstice-2017/), according to astronomers. That’s because meteorologists divide the year into four seasons based on weather patterns, so the summer solstice always occurs later than the first day of summer on the calendar. The summer solstice begins when the tilt of Earth’s axis is most inclined towards the sun directly above the Tropic of Cancer. The [winter solstice](http://time.com/5075624/shortest-day-year-winter-solstice-sunset-time/), which falls on Friday, Dec. 21 this year, is the exact opposite — when the earth’s axis tilted furthest away from the sun, marking the start of winter.  The sun sets on midtown Manhattan and the Chrysler Building on the summer solstice in New York City on June 21, 2017 as seen from Weehawken, NJ. Gary Hershorn—Getty Images The summer solstice happens every year between June 20 and June 22 when the sun reaches its highest elevation in the Northern Hemisphere, making it the longest day of the year with a stretch of sunlight that lasts for 17 hours. The term solstice derives from Latin word “sol” meaning “sun” and “sistere” which means “to make stand, ” according [Dictionary.com](http://www.dictionary.com/e/summer-solstice/). ## When is the 2018 summer solstice? This year, the summer solstice officially starts at 6:07 a.m. E.T. on Thursday, June 21. And while the summer solstice marks the start of the summer, the days are about to get shorter now because the sun is rising later and setting earlier. ## Is the summer solstice different in the Southern Hemisphere? Yes. For those in the Southern Hemisphere, it is the exact opposite — Thursday’s solstice is actually the shortest day of the year and marks the beginning of winter. In the Southern Hemisphere, the summer solstice falls between December 20 and December 22, the same time period as the Northern Hemisphere’s [winter solstice.](http://time.com/5058769/winter-solstice-2017/) ## How is the summer solstice connected to Stonehenge? One of the most well-known celebrations of [summer solstice is at Stonehenge](http://time.com/4376722/summer-solstice-stonehenge/) in the United Kingdom. Some theories speculate that Stonehenge was specifically designed to align with the sun, according to [Salisbury Stonehenge Tours](http://www.stonehenge-tours.com/blog.Astronomical-Alignments-at-Stonehenge.html). Thousands gather at the prehistoric monument to see the sun rise above the Heel Stone, one of the large stones that is at the entrance of Stonehenge. Both the sunrise of the summer solstice and sunset of the winter solstice align with Stonehenge, creating picture-perfect moments for those who travel there to see it. ## Transcript [ MUSIC ] Summer is officially here, which means it's time for summer solstice, aka the longest day of the year. This year, that's June 21st, the northern hemisphere, bringing the longest day and shortest night to 88 % of the world's population. The opposite is true for the southern hemisphere, which will now experience their winter solstice and shortest day of the year. You might think because it's the longest day, it's actually closest to the sun. It's not. The earth rotates 23. 5 degree tilt with the sun everyday. Making a full orbit around the sun once every 365 days and 6 hours. As the planet rotates on its axis, the summer [ UNKNOWN ] occurs when the North poles rages greatest top with the sun. And the sun shines down longer due to its, Positioning as the planet rotates in its axis, the summer solstice occurs when the north pole reaches it's greatest tilt towards the sun. And sun shines down longer due to its positioning. There are areas within the arctic circle that'll see the sun up for 24 hours today. Now while most of the northern hemisphere doesn't catch the sun for an entire day there's still plenty of daylight to soak in. Most places in the U. S. see the sun for about, 14 >> 16 hours on summer solstice. New York is expected to get about 15 hours of sunlight this year while Austin will have 14 hours to bask in the summer rays. But the extra sunshine doesn't necessarily mean it's the hottest day of the year. On this day, the land and oceans absorb some of the energy from the Sun, store it and release it as heat at various rates. Thanks to spring temperatures, the land and oceans are still fairly cool. So air temperatures won't reach their maximum on summer solstice. Eventually, the land and ocean release the stored heat back into the atmosphere, meaning the hottest temperatures typically hit in August or later, depending on your latitude. And it's been a day long celebrated from monuments, at Stonehenge in England to Karnak in Egypt. People around the world have been taking note of the summer solstice for thousands of years. Folks still gather around Stonehenge to watch the sun rise over the structure's heal stone and at the altar in that center. So whether you're planning on going for a nice walk Joining a festival, or dancing the night away. Be sure to enjoy the extra sunshine. The days only get shorter from here on out. 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