Geminid Meteor Shower: NASA to Livestream Annual Highlight of December Skies

Every December we have a chance to see one of our favorite meteor showers – the Geminids. The shower is currently active until Dec. 17 and will peak on the night of Dec. 13 into the morning of Dec. 14, making those hours the best time for viewing the meteor shower.

Geminids
All meteors appear to come from the same place in the sky, which is called the radiant. The Geminids appear to radiate from a point in the constellation Gemini, hence the name “Geminids.” The graphic shows the radiants of 388 meteors with speeds of 35 km/s observed by the NASA Fireball Network in December 2020. All the radiants are in Gemini, which means they belong to the Geminid shower. Credit: NASA

The Geminids are caused by debris from a celestial object known as 3200 Phaethon, whose origin is the subject of some debate. Some astronomers consider it to be an extinct comet, based on observations showing some small amount of material leaving Phaethon’s surface. Others argue that it has to be an asteroid because of its orbit and its similarity to the main-belt asteroid Pallas.

Whatever the nature of Phaethon, observations show that the Geminids are denser than meteors belonging to other showers, enabling them to get as low as 29 miles above Earth’s surface before burning up. Meteors belonging to other showers, like the Perseids, burn up much higher.

The Geminids can be seen by most of the world. Yet, it is best viewed by observers in the Northern Hemisphere. As you enter the Southern Hemisphere and move towards the South Pole, the altitude of the Geminid radiant – the celestial point in the sky where the Geminid meteors appear to originate – gets lower and lower above the horizon. Thus, observers in these locations see fewer Geminids than their northern counterparts.

Besides the weather, the phase of the Moon is a major factor in determining whether a meteor shower will have good rates during any given year. This is because the moonlight “washes out” the fainter meteors, resulting in sky watchers seeing the fewer bright ones. This year, the Moon will be almost 80% full at the peak of the Geminids, which isn’t ideal for our highly regarded meteor shower. Nevertheless, that bright Moon is expected to set around 2:00 a.m. wherever you are located, leaving a couple of hours for meteor watching until twilight.

“Rich in green-colored fireballs, the Geminids are the only shower I will brave cold December nights to see,” said Bill Cooke, lead for NASA’s Meteoroid Environment Office, located at Marshall Space Flight Center in Huntsville, Alabama.

NASA will broadcast a live stream of the shower’s peak Dec. 13-14 via a meteor camera at NASA’s Marshall Space Flight Center in Huntsville, Alabama, (if our weather cooperates!), starting at 8 p.m. CST on the NASA Meteor Watch Facebook page.

Meteor videos recorded by the All Sky Fireball Network are also available each morning to identify Geminids in these videos – just look for events labeled “GEM.”

Learn more about the Geminids below:


Why are they called the Geminids?

All meteors associated with a shower have similar orbits, and they all appear to come from the same place in the sky, which is called the radiant. The Geminids appear to radiate from a point in the constellation Gemini, hence the name “Geminids.”

How fast are Geminids?

Geminids travel 78,000 mph (35 km/s). This is over 1000 times faster than a cheetah, about 250 times faster than the swiftest car in the world, and over 40 times faster than a speeding bullet!

How to observe the Geminids?

If it’s not cloudy, get away from bright lights, lie on your back, and look up. Remember to let your eyes get adjusted to the dark – you’ll see more meteors that way. Keep in mind, this adjustment can take approximately 30 minutes. Don’t look at your cell phone screen, as it will ruin your night vision!

Meteors can generally be seen all over the sky. Avoid watching the radiant because meteors close to it have very short trails and are easily missed. When you see a meteor, try to trace it backwards. If you end up in the constellation Gemini, there’s a good chance you’ve seen a Geminid.

Observing in a city with lots of light pollution will make it difficult to see Geminids. You may only see a handful during the night in that case.

When is the best time to observe Geminids?

The best night to see the shower is Dec. 13/14. Sky watchers in the Northern Hemisphere can go out in the late evening hours on Dec. 13 to see some Geminids, but with moonlight and radiant low in the sky, you may not see many meteors.

Best rates will be seen when the radiant is highest in the sky around 2:00 a.m. local time, including the Southern Hemisphere, on Dec. 14. The Moon will set around the same time. Therefore, observing from moonset until twilight on Dec. 14 should yield the most meteors.

You can still see Geminids on other nights, before or after Dec. 13-14, but the rates will be much lower. The last Geminids can be seen Dec. 17.

How many Geminids can observers expect to see Dec. 13/14?

Realistically, the predicated rate for observers in the northern hemisphere is closer to 30-40 meteors per hour. Observers in the Southern Hemisphere will see fewer Geminids than those in the northern hemisphere – perhaps 25% of rates in the Northern Hemisphere.


Although this year’s conditions are not the best for viewing the Geminid meteor shower, it will still be a good show to catch in our night skies.

And, if you want to know what else is in the sky for December, check out the video below from Jet Propulsion Laboratory’s monthly “What’s Up” video series:

Happy viewing stargazers!

by Lance D. Davis

Experience NASA’s Journey to LCRD Launch

LAUNCH UPDATE:  NASA’s Laser Communications Relay Demonstration (LCRD) is now scheduled to lift off Tuesday, Dec. 7 at 3:04 a.m. CST (4:04 a.m. EST) aboard United Launch Alliance’s Atlas V rocket. Get more details here.


Have you ever witnessed one of NASA’s launches? It’s definitely a sight to see when a rocket takes to the sky, soaring beyond our atmosphere into space.

If you haven’t, you’ll have another chance soon with the Laser Communications Relay Demonstration (LCRD), which will continue NASA’s exploration of laser communications to support future missions to the Moon and throughout our solar system.

Illustration of NASA’s Laser Communication Relay Demonstration
Illustration of NASA’s Laser Communication Relay Demonstration communicating over laser links.
Credits: NASA’s Goddard Space Flight Center

LCRD is scheduled to launch Dec. 5 aboard an Atlas V551 rocket from Cape Canveral Space Force Station in Florida with a two-hour launch window that opens at 3:04 a.m. CST (4:04 a.m. EST).

Live coverage of the launch begins on NASA Live at 2:30 a.m. CST (3:30 a.m. EST), with countdown commentary on NASA Television, the NASA app, and NASA social media.

Register as an LCRD virtual guest to experience NASA’s journey to the LCRD launch. Along with participating online in the launch, you’ll also gain access to curated launch resources, mission information, interaction opportunities, and schedule updates. Following launch, virtual guests will receive a stamp for their virtual guest passport!

Like technology demonstrations that have come before it, LCRD is a giant step towards making operational laser, or optical, communications a reality.

But just how much data can NASA transmit at once with laser communications? To give you an idea, sending a high-resolution map of Mars would take around nine weeks with spacecraft’s current onboard radio systems, but as little as nine days with laser communications. That kind of data rate is much more appealing for future human exploration and science missions.

With the mission operating for at least two years, LCRD will start off “talking” with ground stations in California and Hawaii to test the invisible, near-infrared lasers. Engineers will beam data to and from the satellite – located more than 22,000 miles above Earth – to study and enhance the technology’s performance for an operational mission. LCRD will also help NASA update how astronauts communicate to and from space.

As NASA goes back to the Moon, laser communications can empower sustainable communications and help us prepare for a human presence on Mars.

Get the full LCRD experience below:

The Mission:

For Fun:

For Students: 

Watch, Engage on Social Media:

Developed and led by Goodard Space Flight Center in Greenbelt, Maryland, LCRD is funded by the Technology Demonstration Missions program, located at Marshall Space Flight Center in Huntsville, Alabama, which is part of the Space Technology Mission Directorate at NASA Headquarters in Washington. Additionally, it’s funded by the Space Communications and Navigation program, also at NASA Headquarters.

Learn more about LCRD.

by Lance D. Davis

Longest Partial Lunar Eclipse in Centuries Coming as ‘Almost’ Total Lunar Eclipse

We have a rare opportunity to witness the longest partial lunar eclipse in nearly 600 years. If the weather permits, it will grace our sky on the night of Nov. 18 and early in the morning Nov. 19 across all of the United States.

A lunar eclipse happens when the Sun, Earth, and Full Moon form a near-perfect lineup in space. A partial lunar eclipse occurs when only a portion of the Moon passes through the Earth’s darkest shadow. During this type of eclipse, a part of the Moon will darken to a dim orange or red as it moves through the Earth’s shadow.

Partial lunar eclipse image
When only a part of the moon enters Earth’s shadow, the event is called a partial lunar eclipse. Credit: Brad Riza

The upcoming eclipse will be visible throughout much of the globe where the Moon appears above the horizon during the eclipse, including North and South America, Eastern Asia, Australia, and the Pacific Region. North America will have the best location to see the entirety of the eclipse.

The partial eclipse will begin a little after 1:00 a.m. CST on Nov 19 (11:00 pm PST on Nov 18.), reaching its maximum at 3:00 a.m. CST. Depending on your local time zone, it’ll happen earlier or later in the evening for you. It will last 3 hours and 28 minutes, making it the longest partial eclipse of this century and the longest in 580 years.

This is a remarkably deep partial eclipse as up to 97% of the Moon’s diameter will be covered by Earth’s darkest shadow. Only a thin slice of the Moon will be exposed directly to the Sun at maximum eclipse. Expect to see the rest of the Moon take on the orange-reddish colors, appearing as an “almost” total lunar eclipse.

Total Lunar Eclipse
A telescopic visualization of the 2021 total lunar eclipse.
Credit: NASA’s Scientific Visualization Studio

You won’t need any special glasses to see the partial lunar eclipse, unlike when viewing a solar eclipse. Just wake up, get out of the bed, and go outside to see the last lunar eclipse of 2021!

Learn more about eclipses here and enjoy this spectacle as you watch the skies!

by Lance D. Davis

International Observe the Moon Night 2021

Everyone, everywhere, every year is invited to celebrate with fellow Moon enthusiasts around our planet for International Observe the Moon Night – a worldwide public event encouraging observation, appreciation, and understanding of the Moon and its connection to NASA exploration and discovery.

Join NASA’s Marshall Space Flight Center on Oct. 16, 2021, for the Virtual Observation Party at 6:00 p.m. CDT via the Facebook event page.

observe the moon night
Image Credit: NASA/Vi Nguyen

This virtual event is brought to you by the Planetary Missions Program Office at Marshall and the U.S. Space & Rocket Center. Additionally, it will include a planetarium show and interviews with planetary and citizen scientists. There will also be an interview about the Artemis missions. So, don’t miss out on this fun, informative program!

It’s a great time to celebrate the Moon with people all over Earth as excitement grows about NASA returning to our nearest celestial neighbor with the Artemis missions. Artemis will land the first woman and first person of color on the Moon, using innovative technologies to explore areas of the lunar surface that have never been discovered before.

Since 2010, the celebration has occurred annually in September or October when the Moon is around first quarter – a great phase for excellent viewing opportunities.

Whether it’s outdoors, at home, online, or wherever you may be, you are encouraged to be a part of International Observe the Moon Night. Please remember to follow your local health and safety guidelines.

Learn more and find other events here. Enjoy the celebration!

by Lance D. Davis

September Equinox 2021 is Coming!

In meteorology, the fall season begins on Sept. 1, however, the September (or fall) equinox gives us the green light to welcome the astronomical fall season in the Northern Hemisphere (and astronomical spring season in the Southern Hemisphere). This happens Sept. 22, 2021, at 19:21 UTC, which is 2:21 p.m. CDT for us in North America.

illustration of the March (spring) and September (fall or autumn) equinoxes
An illustration of the March (spring) and September (fall or autumn) equinoxes. During the equinoxes, both hemispheres receive equal amounts of daylight. Credit: NASA/JPL-Caltech

Along with marking the beginning of astronomical fall, the Sun will be exactly above Earth’s equator, moving from north to south, making day and night nearly equal in length – about 12 hours – throughout the world.

At the North Pole, over the upcoming days, the Sun will sink below the horizon for a kind of twilight from now until sometime in October when it will be completely dark, according to NASA solar scientist Mitzi Adams. Spring twilight at the North Pole begins a few weeks before the vernal, or spring, equinox in March, when the Sun rises above the horizon again.

This only happens twice in Earth’s year-long trip around the Sun. The rest of the year, the Sun shines unevenly over the Northern and Southern Hemispheres. That’s because Earth’s axis is tilted with respect to the Sun-Earth plane. But on these special days – the spring and fall equinoxes – the Sun shines almost equally on the Northern and Southern hemispheres.

Equinox Solstice Info Graphic
Click to view larger. Credit: NASA/Space Place

In the Northern hemisphere, the September equinox marks the start of a period bringing us later sunrises and earlier sunsets. We will also feel cooler days with chillier winds, and dry, falling leaves.

The people of ancient cultures used the sky as a clock and calendar. They knew that the Sun’s path across the sky, length of daylight, and location of sunrise and sunset all shifted in a regular way throughout the year. Additionally, earlier civilizations built the first observatories, like Stonehenge in Wiltshire, England, and the Intihuatana stone in Machu Picchu, Peru, to follow the Sun’s annual progress.

Today, we celebrate the equinox as an astronomical event caused by Earth’s tilt on its axis and its motion in orbit around the Sun.

Enjoy the new season – whichever side of the globe you’re on!

by Lance D. Davis

August 2021 Brings Rare Seasonal ‘Blue Moon’

This month we’ll get to see a Full Moon on Aug. 22, 2021, known by some early Native American tribes of the northeastern United States, as the Sturgeon Moon. The name was given to the Moon because the large sturgeon fish of the Great Lakes, and other major lakes, were more easily caught at this time of year. But that’s not all! We also get to see a Blue Moon!

We’ve all heard the phrase “once in a Blue Moon,” which usually refers to something that rarely happens. Blue Moons do sometimes happen in Earth’s night sky, giving rise to this phrase. But what is a Blue Moon?

One way to make a Blue Moon is by using a blue filter.
One way to make a Blue Moon is by using a blue filter. Credit: NASA

Well, we have two kinds of Blue Moons – monthly and seasonal.

A monthly Blue Moon is the second Full Moon in a calendar month with two Full Moons. Then, there’s a seasonal Blue Moon – the third Full Moon of an astronomical season that has four Full Moons.

In astronomy, a season is the period of time between a solstice and equinox, or vice versa. Each season – winter, spring, summer or fall – lasts three months and usually has three Full Moons, occurring about 30 days apart. Because June’s Full Moon came just a few days after the June (Summer) solstice, we will see four Full Moons in the current summer season, which ends at the September equinox on Sept. 22.

The third Full Moon – our seasonal Blue Moon – will happen on Aug. 22.  All Full Moons are opposite the Sun, as viewed from Earth, rising fully illuminated at local time around sunset and setting around sunrise.

Perhaps you’re wondering if the Moon ever actually takes on a blue color. Well, Blue Moons that are blue in color are extremely rare and have nothing to do with the calendar or the Moon’s phases; they don’t have to be Full Moons either. When a blue-colored Moon happens, the blue color is the result of water droplets in the air, certain types of clouds, or particles thrown into the atmosphere by natural catastrophes, such as volcanic ash and smoke. Also, blue-colored Moons in photos are made using special blue filters for cameras or in post-processing software.

In 1883, an Indonesian volcano called Krakatoa produced an eruption so large that scientists compared it to a 100-megaton nuclear bomb. Ash from the Krakatoa explosion rose as high into the atmosphere as 80 kilometers (50 miles). Many of these ash particles can be about 1 micron in size, which could scatter red light and act as a blue filter, resulting in the Moon appearing blue.

Blue-colored Moons appeared for years following the 1883 eruption. Many other volcanoes throughout history, and even wildfires, have been known to affect the color of the Moon. As a rule of thumb, to create a bluish Moon, dust or ash particles must be larger than about 0.6 micron, which scatters the red light and allows the blue light to pass through freely. Having said all of that, what we call a Blue Moon typically appears pale grey, white or a yellowish color – just like the Moon on any other night.

Generally, Blue Moons occur every 2 to 3 years. Our last Blue Moon was on Oct. 31, 2020 – the night of Halloween. Mars was red and very large, since it was closer to Earth, and it was seen in the sky near the Blue Moon. Coincidently, this year’s Blue Moon will appear near planets again, but this time Jupiter and Saturn! We won’t see another Blue Moon until August 2023.

Learn more about Earth’s Moon here.

by Lance D. Davis

How many Perseids will I see in 2021?

By Bill Cooke, NASA Meteoroid Environments Office

Many Perseid-related news stories and social media posts state that the maximum rate is about 100 meteors per hour, which is a lot. So, folks get excited and go out on the peak night, braving mosquitos and other nightly hazards. But they are often disappointed; we routinely hear, “I went out and only saw a few meteors. Not even 20, much less 100!” And they would be right. The problem is that the 100 per hour is a theoretical number used by meteor scientists and does not convey what people are actually going to see.

In the 1980’s, meteor researchers were searching for a way to compare the meteor shower rates observed by various individuals and groups across the globe. People were reporting the rates, but the differences in sky conditions, radiant altitude and observer eyesight made getting a comprehensive view of shower activity difficult.

So, the meteor researchers put their heads together and came up with the concept of a ZHR, or Zenithal Hourly Rate. The ZHR is what you get after you correct the observed rates for the sky conditions, the altitude of the radiant above the horizon and observer biases. In other words, it is basically what a perfect observer would see under perfect skies with the meteor shower radiant straight overhead – which never happens!

The often-quoted ZHRs overestimate the meteor rates people actually see – sometimes by a lot. Fortunately, we can take the ZHR and invert things to get the hourly rates for certain locations and circumstances – it’s only math, after all. We have done this for select locations in the United States, producing the following maps.

These maps show the hourly rates that can be expected on the night of the Perseid shower’s peak, provided there are no clouds in the sky. (It’s hard to account for partial cloud cover.)

These rates assume you are out in the country, where lots of stars and the Milky Way are visible and no clouds, of course:

Perseids in CountrySo, instead of 100 Perseids per hour, people in the U.S. can reasonably expect to see around 40-ish Perseids in the hour just before dawn on the peak nights. That’s about one every couple of minutes – not bad. However, we are assuming you are out in the country, well away from cities and suburbs.

What rates can you expect if you want to do your Perseid watching from the neighborhood? We also computed that:

Perseids in SuburbsThe brighter skies of the suburbs greatly cut down the rates. We have gone from a Perseid every couple of minutes to one every 6-7 minutes – a factor of three reduction. This explains the great disappointment expressed by many casual Perseid watchers; they go outside, expecting to see at least a meteor a minute and end up with 10 or less in an hour. The brightness of your sky is everything in meteor observing – you have to get away from the lights!

But what about those in cities? The rates are close to zero:

Perseids in CityUgh! City dwellers might see a Perseid or two in an hour. Not very inspiring. Perhaps the only good news is that, if someone in a city sees a Perseid, it has to be really, really bright and spectacular.

Want to see Perseids? Then head out into the dark – it’s worth it!

Check out our previous blog post, The Perseids are on the Rise, for more information on the Perseids and tips on how to observe them.

The Perseids are on the Rise!

It’s time again for one of the biggest meteor showers of the year! The Perseids are already showing up in our night skies—and when they peak in mid-August, it’s likely to be one of our most impressive skywatching opportunities for a while.

Perseid Meteor image
In this 30 second exposure taken with a circular fish-eye lens, a meteor streaks across the sky during the annual Perseid meteor shower on Friday, Aug. 12, 2016 in Spruce Knob, West Virginia. Photo Credit: (NASA/Bill Ingalls)

Our meteor-tracking cameras spotted their first Perseid on July 26, but your best chance to see them will start the night of Aug. 11. With the crescent moon setting early, the skies will be dark for the peak viewing hours of midnight (local time) to dawn on Aug. 12.

Perseid activity
This chart shows expected levels of Perseid activity for July and August 2021, relative to the peak on Aug. 11-13, ignoring the effects of the Sun, Moon, and clouds. All times are in UTC. Credits: (NASA/MEO/Bill Cooke)

If you’re in the Northern Hemisphere, and far away from light pollution, you might spot more than 40 Perseids an hour! (If you’re in a city, you may only see a few every hour; skywatchers in the Southern Hemisphere will also see fewer Perseids, with none visible below about 30 degrees south latitude.) The night of Aug. 12-13 will be another great opportunity to see the Perseids: with a full Moon (and lower meteor activity) during the Perseids’ peak in 2022 and a waning crescent high in the sky for 2023, this might be your best chance to do some summer skywatching for a few years.

Find somewhere comfortable, avoiding bright lights as much as possible (yes, including your phone), and give your eyes some time to adjust to the dark—up to half an hour if you can. The Perseids will appear as quick, small streaks of light: they get their name because they look like they’re coming from the direction of the constellation Perseus (near Aries and Taurus in the night sky), but Perseids in that area can be hard to spot from the perspective of Earth. So just look up and enjoy the show!

If you can’t see the Perseids where you live, join NASA to watch them on social media! Tune in overnight Aug. 11-12 (10 PM–5 AM CDT; 3–10 AM UTC) on Facebook, Twitter and YouTube to look for meteors with space fans from around the world. If skies are cloudy the night of Aug. 11, we’ll try again the same time on Aug. 12-13. Our livestream is hosted by the Meteoroid Environment Office at NASA’s Marshall Space Flight Center, which tracks meteors, fireballs, and other uncommon sights in the night sky to inform the public and help keep our astronauts and spacecraft safe.

Where do the Perseids *actually* come from?

The Perseids are fragments of the comet Swift-Tuttle, which orbits between the Sun and beyond the orbit of Pluto once every 133 years. Every year, the Earth passes near the path of the comet, and the debris left behind by Swift-Tuttle shows up as meteors in our sky. (Don’t worry, there’s no chance that we’ll run into the actual comet anytime soon.)

Where can I go to learn more?

We’ve got some great space-rock lessons for students, starting with the biggest question: what’s the difference between an asteroid and a meteor? Our NASA Space Place site also has a kid-friendly introduction to meteor showers in general. If you’re looking for something a little more hands-on, try this asteroid-building classroom activity—or, for an older audience, learn how to describe rocks like a NASA scientist.

And, if you want to know what else is in the night sky this month, check out the video below from Jet Propulsion Laboratory’s monthly “What’s Up” video series:

Happy skywatching!

by Brice Russ

See the Strawberry Moon – 2021’s Last Supermoon!

Our planet’s natural satellite – better known as the Moon – will appear opposite the Sun and fully illuminated on June 24, 2021, at 18:40 UTC, which is 1:40 p.m. CDT (UTC-5). This full Moon is quite special for two reasons: it’s a Strawberry Moon and the last supermoon of the year!

The Strawberry Moon marks the last full Moon of spring or the first full Moon of summer. Towards the end of June, the Moon usually sits in a lower position in the sky and shines through more of our atmosphere. Because of this, our Moon can sometimes give off a pinkish hue.

supermoon
A supermoon rises behind the U.S. Capitol, Monday, March 9, 2020, in Washington. Credits: NASA/Joel Kowsky

Surprisingly, the name likely has more to do with the time of the year it occurs than its unusual pink shade. Some Native American tribes referred to this full moon as the Strawberry Moon because it signaled a time for gathering ripening strawberries and other fruits.

A supermoon occurs when a full Moon coincides with the Moon’s closet approach to Earth in its elliptical orbit, a point known as perigee. During every 27-day orbit around Earth, the Moon reaches both its perigee, about 226,000 miles from Earth, and its farthest point, or apogee, about 251,000 miles from Earth.

Although supermoon is not an official astronomical term, it’s typically used to describe a full Moon that comes within at least 90% of perigee. In this phase, the Moon appears larger and brighter than usual. A new Moon can also be a supermoon. However, we typically do not see a new Moon since it is between Earth and the Sun, and therefore not illuminated.

If you’re in the daylight at the time of the Super Strawberry Moon, look for a better view during its moonrise, which is about 20 minutes after sunset, local time.

The Super Strawberry Moon will be the last of four supermoons for 2021. Supermoons only happen three to four times a year, and always appear consecutively. The last three supermoons occurred on May 26, April 27, and March 28.

Skywatchers, please enjoy the sunset in the west, and if you look toward the east, you may notice the subtle pink hue of our Super Strawberry Moon!

by Lance D. Davis

June Solstice Brings Summer, Winter Seasons

The June solstice gives us the green light to welcome the summer season in the Northern Hemisphere and winter season in the Southern Hemisphere. This happens June 21, 2021, at 03:32 UTC, but for us in North America, that’s June 20 at 10:32 p.m. CDT (UTC-5).

In meteorology, summer begins on June 1. Yet, June 21 is perhaps the most widely recognized day when summer starts in the northern half of our planet and winter starts in the southern half. This astronomical beginning of the summer season and long-held, universal tradition of celebrating the solstice have allowed us to treasure this time of warmth and light.

Summer solstice explanation
During the solstices, Earth reaches a point where its tilt is at the greatest angle to the plane of its orbit, causing one hemisphere to receive more daylight than the other. Credits: NASA/Genna Duberstein

Along with marking the beginning of summer, this will also be the longest day of the year in the Northern Hemisphere. We will begin to see early dawns, long days, late sunsets, and short nights. On the solstice, our Sun will reach its highest point as it crosses the sky. Meanwhile, south of the equator, winter will begin!

The ancient cultures knew that the Sun’s path across the sky, length of daylight, and location of the sunrise and sunset all shifted in a regular way throughout the year. Additionally, people built monuments, like Stonehenge, to follow the Sun’s annual progress, to worship the Sun, and to predict its movements.

Earth's seasons
Click to view larger. Credit: NASA/Space Place

Today, we celebrate the solstice as an astronomical event caused by Earth’s tilt on its axis and its motion in orbit around the Sun.

Earth’s axis may be imagined as an imaginary pole going right through the center of our planet 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.

Earth doesn’t orbit upright; its axis is always tilted 23.5˚ with respect to the Sun-Earth line, which is why we have seasons. During the June solstice compared to any other time of the year, the north pole is tipped more directly toward the Sun, and the south pole is tipped more directly away from the Sun. As a result, all locations north of the equator see days longer than 12 hours and all locations south see days shorter than 12 hours.

Enjoy the new season – whichever half of the globe you’re in!

by Lance D. Davis