NASA – Watch the Skies

Jupiter to Reach Opposition, Closest Approach to Earth in 59 Years!

Stargazers can expect excellent views of Jupiter the entire night of Monday, Sept. 26 when the giant planet reaches opposition. From the viewpoint of Earth’s surface, opposition happens when an astronomical object rises in the east as the Sun sets in the west, placing the object and the Sun on opposite sides of Earth.

Jupiter’s opposition occurs every 13 months, making the planet appear larger and brighter than any other time of the year. But that’s not all. Jupiter will also make its closest approach to Earth since 1963 – almost six decades ago! This happens because Earth and Jupiter do not orbit the Sun in perfect circles – meaning the planets will pass each other at different distances throughout the year. Jupiter’s closest approach to Earth rarely coincides with opposition, which means this year’s views will be extraordinary. At its closest approach, Jupiter will be approximately 367 million miles in distance from Earth, about the same distance it was in 1963. The massive planet is approximately 600 million miles away from Earth at its farthest point.

Photo of Jupiter with Red Spot — This photo of Jupiter, taken from the Hubble Space Telescope on June 27, 2019, features the Great Red Spot, a storm the size of Earth that has been raging for hundreds of years. Credits: NASA, ESA, A. Simon (Goddard Space Flight Center), and M.H. Wong (University of California, Berkeley)

“With good binoculars, the banding (at least the central band) and three or four of the Galilean satellites (moons) should be visible,” said Adam Kobelski, a research astrophysicist at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “It’s important to remember that Galileo observed these moons with 17th century optics. One of the key needs will be a stable mount for whatever system you use.”

Kobelski recommends a larger telescope to see Jupiter’s Great Red Spot and bands in more detail; a 4 inch-or-larger telescope and some filters in the green to blue range would enhance the visibility of these features.

According to Kobelski, an ideal viewing location will be at a high elevation in a dark and dry area.

“The views should be great for a few days before and after Sept. 26,” Kobelski said. “So, take advantage of good weather on either side of this date to take in the sight. Outside of the Moon, it should be one of the (if not the) brightest objects in the night sky.”

As the Moon rose over the Wasatch Mountains near Salt Lake City on Feb. 27, 2019, the planet Jupiter could be seen, along with three of its largest moons. Stargazers should have a similar view during Jupiter in Opposition on Monday, Sept. 26. Credits: NASA/Bill Dunford

Jupiter has 53 named moons, but scientists believe that 79 moons have been detected in total. The four largest moons, Io, Europa, Ganymede, and Callisto, are called the Galilean satellites. They are named after the man who first observed them in 1610, Galileo Galilei. In binoculars or a telescope, the Galilean satellites should appear as bright dots on either side of Jupiter during opposition.

NASA’s Juno spacecraft, which has been orbiting Jupiter for six years, is dedicated to exploring the planet and its moons. Juno began its journey in 2011 and reached Jupiter five years later. Since 2016, the spacecraft has provided incredible images and data about Jupiter’s lively atmosphere, interior structures, internal magnetic field, and magnetosphere.

Scientists believe studying Jupiter can lead to breakthrough discoveries about the formation of the solar system. Juno’s mission was recently extended until 2025 or until the end of the spacecraft’s life. Learn more about Juno.

The next major project for Jupiter exploration is the Europa Clipper. This spacecraft will explore Jupiter’s iconic moon, Europa, which is known for its icy shell and vast ocean that lies beneath its surface. NASA scientists aim to find whether Europa has conditions able to sustain life. Europa Clipper’s targeted launch is currently scheduled for no earlier than October 2024.

Learn more about the giant planet. And if you want to know what else is happening in the sky for September, check out Jet Propulsion Laboratory’s latest “What’s Up” video:

by Lane Figueroa

Meteor Showers to Bookend Overnight Skywatching Opportunities in May

As the spring season continues, May could prove to be of great interest for stargazers and space enthusiasts – with a pair of potentially active meteor showers opening and closing the month.

“Meteors aren’t uncommon,” Bill Cooke said, who leads NASA’s Meteoroid Environment Office at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “Earth is bombarded every day by millions of bits of interplanetary detritus speeding through our solar system.”

A meteor mosaic comprised of 99 images, using a blue filter, of the Eta Aquariids observed during the early morning hours from April 30 to May 8, 2013.
Credits: NASA All Sky Fireball Network

Most particles are no bigger than dust and sand. Hitting the upper atmosphere at speeds up to 45 miles per second, they flare and burn up. On any given night, the average person can see from 4 to 8 meteors per hour. Meteor showers, however, are caused by streams of comet and asteroid debris, which create many more flashes and streaks of light as Earth passes through the debris field.

“It’s a perfect opportunity for space enthusiasts to get out and experience one of nature’s most vivid light shows,” Cooke said.

Eta Aquariids (May 5-6)

First up, on the night of May 5 and early hours of May 6, around 3:00 am CDT, is the eta Aquariid shower, caused by the annual encounter with debris from Halley’s comet – remnants of the comet’s tour through the solar system once every 75 or 76 years. Its radiant – or the point in the night sky from which the meteor shower appears to originate – is the constellation Aquarius. The shower is named for the brightest star in that constellation, eta Aquarii.

A 2013 eta Aquariid composite from a camera used in New Mexico.
Credits: NASA Meteoroid Environment Office

Until Halley’s comet is next visible from Earth in 2061, only the eta Aquariids – and their fall counterpart, the Orionid meteor shower, which is visible each October – mark the passage of this solar system visitor.

“It will be interesting to see if the rates are low this year, or if we will get a spike in numbers before next year’s forecast outburst,” Cooke said.

The annual meteor shower has the best rates for those in the Southern Hemisphere, but even in the Northern Hemisphere, if weather conditions are right, there is a possibility of seeing up to 30 meteors per hour. The waxing crescent Moon will set before the eta Aquariid radiant gets high in the sky, leaving dark skies for what should be an excellent show. Best viewing happens after 3 AM local time, so get up early.

Tau Herculids (May 30-31)

A possible newcomer this year is the tau Herculid shower, forecast to peak on the night of May 30 and early morning of May 31.

Back in 1930, German observers Arnold Schwassmann and Arno Arthur Wachmann discovered a comet known as 73P/Schwassmann-Wachmann, or “SW3, which orbited the Sun every 5.4 years. Being so faint, SW3 wasn’t seen again until the late 1970s, seeming pretty normal until 1995, when astronomers realized the comet had become about 600 times brighter and went from a faint smudge to being visible with the naked eye during its passage. Upon further investigation, astronomers realized SW3 had shattered into several pieces, littering its own orbital trail with debris. By the time it passed our way again in 2006, it was in nearly 70 pieces, and has continued to fragment further since then.

If it makes it to us this year, the debris from SW3 will strike Earth’s atmosphere very slowly, traveling at just 10 miles per second – which means much fainter meteors than those belonging to the eta Aquariids. But North American stargazers are taking particular note this year because the tau Herculid radiant will be high in the night sky at the forecast peak time. Even better, the Moon is new, so there will be no moonlight to wash out the faint meteors.

“This is going to be an all or nothing event. If the debris from SW3 was traveling more than 220 miles per hour when it separated from the comet, we might see a nice meteor shower. If the debris had slower ejection speeds, then nothing will make it to Earth and there will be no meteors from this comet,” Cooke said.

Learn more about meteors and meteorites. Also, if you want to know what else is in the sky for May, check out the latest “What’s Up” video from Jet Propulsion Laboratory:

Enjoy all this month has to offer as you watch the skies!

by Rick Smith

December Solstice Brings Winter, Summer Seasons

In meteorology, Earth’s winter season for the Northern Hemisphere and summer season for the Southern Hemisphere began on Dec. 1, 2021. However, the December solstice brings in the astronomical winter and summer seasons, respectively, for the two hemispheres of our planet. This will happen on Dec. 21 at 15:59 UTC, which is 9:59 a.m. CST in the United States.

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

Solstices come twice a year. For the Northern Hemisphere, the summer (June) solstice occurs around June 20-21, and the winter (December) solstice happens around Dec. 21-22. At the solstice, the Sun’s path appears farthest north or south, depending on which half of the planet you’re on. Seasons change on Earth because the planet is slightly tilted on its axis as it travels 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.

Although the tilt of the Earth as compared to the plane of its orbit around the Sun is more or less constant (23.5˚), at the December solstice, the Northern Hemisphere receives the most indirect sunlight, causing cooler temperatures. The Southern Hemisphere receives the most direct sunlight, causing warmer temperatures, so it is summer there. At the June solstice, this effect reverses and the Northern Hemisphere receives the most direct sunlight, causing warmer temperatures, and the Southern Hemisphere receives the most indirect sunlight, causing cooler temperatures.

The December solstice brings the shortest day and longest night of the year for locations in the northern half of the globe, like the U.S., while the southern half of the globe is experiencing its longest day and shortest night. Therefore, all locations north of the equator see daylight shorter than 12 hours and all locations south see daylight longer than 12 hours.

After the winter solstice in the Northern Hemisphere, the days will get longer and the nights shorter until the summer solstice on June 21, 2022, when things reverse. The March equinox on March 20, 2022, will mark the beginning of the astronomical spring season and the September equinox on September 22, 2022, will mark the beginning of astronomical fall.

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 in England and the Torreon in Machu Picchu, Peru, to follow the Sun’s annual progress and predict its movements.

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

No matter where you are on Earth’s globe – this is your time to celebrate this seasonal change!

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.

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. 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

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.

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.

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 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

May’s Full Moon Comes with Supermoon Eclipse

As we approach month’s end, there is not one, not two, but three celestial events happening with our Moon!

The Moon will be located on Earth’s opposite side from the Sun and fully illuminated May 26, 2021, at 6:13 a.m. CDT. This Full Moon was known by early Native American tribes as the Flower Moon because this was the time of year when spring flowers appeared in abundance.

Compared to other Full Moons in 2021, the Flower Moon will have the nearest approach to Earth, making it appear as the closet and largest Full Moon of the year. This is what is commonly referred to as a “supermoon”. Yet, it’s not just bringing brightness and size. May’s supermoon is also bringing a “super power” to change its color, and the color is red!

A telescopic visualization of the 2021 total lunar eclipse.
Credits: NASA’s Scientifc Visualization Studio

Mars is most commonly known as the Red Planet. But have you ever witnessed our own planet’s Moon turn red? If you haven’t, you’ll get your chance with this year’s only total lunar eclipse also happening May 26! It’s been nearly two and a half years since the last one.

A total lunar eclipse occurs when the Moon passes completely through the Earth’s dark shadow, or umbra. During this type of eclipse, the Moon will gradually get darker, taking on a rusty or blood-red color. The color is so striking that lunar eclipses are sometimes called Blood Moons.

The total eclipse phase will be visible near moonset in the western United States and Canada, all of Mexico, most of Central America and Ecuador, western Peru, and southern Chile and Argentina. The eclipse can be seen in its entirety in eastern Australia, New Zealand, and the Pacific Islands, including Hawaii. Unlike a solar eclipse, you won’t need special glasses to view this lunar eclipse, just go outside and keep your head to the sky!

“Folks in Hawaii and the Aleutian Islands will get to see the entirety of this eclipse – it will be quite a show for them,” said Bill Cooke, Lead, NASA Meteoroid Environments Office.

The eclipse is set to begin May 26 at 1:46 a.m. PDT, with the Moon entering the darkest part of the Earth’s shadow at 2:45 a.m. Part of it will remain in the umbra until 5:53 a.m. To catch totality – the period when all of the Moon’s surface is blanketed by the Earth’s dark shadow – look up between 4:11 and 4:26 a.m.

We haven’t had a total lunar eclipse occur with a supermoon in almost six years, and the next total lunar eclipse won’t happen over North America until May 2022.

Enjoy this spectacle of the sky!

by Lance D. Davis

Earth Day: NASA Celebration, Lyrids to Peak

Earth Day – also known as the birth of the modern environmental movement – is Thursday, April 22, 2021. It began in 1970, giving a voice to an emerging public consciousness about the state of our planet. The celebration is widely recognized as the largest secular observance in the world, with more than a billion people participating annually in support of preserving the health and beauty of our planet.

In observance of Earth Day, NASA will host a virtual event April 21-24 to show how we are #ConnectedByEarth with a week of online events, stories, and resources. The event platform will feature live presentations by NASA scientists, as well as interactive chats with Earth science experts. Visitors can explore the connections between Earth’s atmosphere, water cycle, forests, fields, cities, ice caps, and climate through videos and interactive science content, a kid-friendly fun zone, a scavenger hunt, hundreds of downloadable resources, and more. Some content also will be available in Spanish.

On Earth Day at 11 a.m. EDT, NASA will host a special live conversation with Grammy-nominated singer-songwriter Shawn Mendes and five people living and working in space: NASA astronauts Mike Hopkins, Victor Glover, Dr. Shannon Walker, and Mark Vande Hei; and Japan Aerospace Exploration Agency (JAXA) astronaut Soichi Noguchi. The event will air live on NASA Television, the NASA app, and the agency’s website. Learn more about NASA’s Earth Day plans and free online registration.

After several months of a meteor drought in 2021, we also have the annual Lyrid meteor shower coming up on Earth Day. The Lyrids will peak in the predawn hours of Earth Day (April 22). If you miss the peak, the wee hours of the following morning (April 23) offer another chance to see this shower, though the number of meteors will be down about 30% from the night of the 21st/22nd.

Composite image of Lyrid and not-Lyrid meteors over New Mexico from April, 2012. Credits: NASA/ MSFC/ Danielle Moser

Observers in the Northern Hemisphere will see the most Lyrids, with the best time to watch between midnight and dawn. Although you’ll see a fairly bright Moon in the evening sky, it will set before the shower peaks near dawn. Peak rates for the Lyrids are around 10-20 meteors per hour. The meteors will appear to radiate from the constellation Lyra, but they can appear anywhere in the sky, which is why it is important to lie on your back and take in as much sky as possible.

The Lyrids is among the oldest of known meteor showers, with records going back for 2,700 years or more. It is produced by dust particles left behind by Comet C/1861 G1 Thatcher, which was discovered in 1861. The shower runs annually from April 16-25.

For more on meteor showers, visit the NASA Meteor Watch Facebook page.

Happy Earth Day and meteor watching!

by Lance D. Davis

Jupiter-Saturn Great Conjunction: Watch Best View Since Middle Ages!

by Lance D. Davis

Stargazers get ready for a nice treat as we are about to witness a super-rare planetary alignment not seen for almost 800 years!

Our solar system’s two biggest worlds – the mighty Jupiter followed by the glorious ringed Saturn – will appear in the sky next to each other at their closest since 1623 and closest visible from Earth since the Middle Ages in 1226. This will happen on Dec. 21, 2020, during an event called a “great conjunction.”

Astronomers use the word conjunction to describe close approaches of planets and other objects on our sky’s dome. They use great conjunction specifically for Jupiter and Saturn because of the planets’ top-ranking sizes.

A graphic made from a simulation program, showing a view of the 2020 great conjunction through the naked eye just after sunset at approximately 5:15 p.m. (EST) on Dec. 21.
Credit: NASA

Great conjunctions between Jupiter and Saturn happen every 20 years, making the planets appear to be close to one another. This closeness occurs because Jupiter orbits the Sun every 12 years, while Saturn’s orbit takes 30 years, causing Jupiter to catch up to Saturn every couple of decades as viewed from Earth.

The last conjuction between these planets took place on May 28, 2000. This year’s conjunction occurs on Dec. 21, which coincidentally is also the date of the winter solstice in the Northern Hemisphere. The 2020 conjunction is unique because of how close Jupiter and Saturn will appear. In most conjunctions, Jupiter and Saturn pass within a degree of each other. This year, they will pass 10 times closer to each other – the closest in nearly 400 years.

view of the 2020 great conjunction through a telescope — A graphic made from a simulation program, showing the view of the 2020 great conjunction
through a telescope at approximately 5:15 p.m. (EST) on Dec. 21. Credit: NASA

Currently, you can watch Jupiter and Saturn get closer in Earth’s sky each evening until their grand finale on Dec. 21. Just look for them shortly after sunset, shining brightly and low in the southwestern sky. Also, tune in to NASA Science Live or NASA Facebook on Dec. 17 at 3:00 p.m. EST (2:00 p.m. CST) and learn how to see Jupiter and Saturn’s great conjunction.

During the great conjunction, the giant planets will appear just a tenth of a degree apart – that’s about the thickness of a dime held at arm’s length! This means the two planets and their moons will be visible in the same field of view through a small telescope. Truly, this is a once-in-a-lifetime event!

Some astronomers suggest the pair will look like an elongated star and others say the two planets will form a double planet. To know for sure, we’ll just have to look and see. Either way, take advantage of this opportunity because Jupiter and Saturn won’t appear this close in the sky until 2080!

Additional Information & Resources:

› Learn how to photograph the Jupiter-Saturn conjunction.
› Read about mission visits to Jupiter and Saturn.
› Find an astronomy club or event near you!

Total Solar Eclipse to Cast Shadow on South America

by Lauren Lambert

What is a Solar Eclipse?

A solar eclipse is a natural phenomenon that occurs when the Moon passes between the Sun and Earth. This event happens when the Moon completely blocks the Sun and the Moon’s shadow falls onto a portion of the Earth’s surface.

There are three types of solar eclipses: total, partial and annular. During a total solar eclipse, observers can witness daytime twilight because the disk of the Moon blocks 100% of the Sun. During a partial solar eclipse, the Moon is not entirely covering the Sun and you will likely not notice any difference in light intensity. You may only notice a subtle difference if the partial eclipse is close to total and you go outside at maximum eclipse. Lastly, an annular eclipse can be observed when the Moon is at apogee, or the farthest from Earth within its elliptical orbit. This causes a ring of light, or annulus, to be visible around the Moon, which is sometimes referred to as the “ring of fire.”

total solar eclipse image — During the total solar eclipse, the Sun’s visible-light corona (meaning crown), only visible at maximum eclipse from within the path of totality, is seen here as a crown of white light extending from around the edge of the eclipsing Moon. The red loops of material also seen around the edge, are called prominences, in which magnetic fields enclose hot solar material. Credit: NASA/Armstrong’s Gulfstream III.

Total eclipses are of particular interest to solar scientists, because with the Moon blocking the bright light of the Sun, you can see the Sun’s atmosphere from the ground. Solar scientists at Marshall Space Flight Center, and around NASA, make use of telescopes called coronagraphs that block the Sun so they can see the dim atmosphere, the corona, around it. But — given how perfectly the Moon lines up with the Sun — you can see the atmosphere closer to the surface of the Sun than we even can with our telescopes in space.

The shadow of the Moon on a planet during an eclipse can be described using three terms: umbra, antumbra and penumbra. The umbra is the shadow that is cast when the Moon completely covers the Sun and is where the path of totality falls. If the Moon is further away from the Earth, it is unable to block the Sun entirely. The Sun appears as a ring of light around the Moon. In this case, the shadow is known as the antumbra, or path of annularity, and occurs during an annular eclipse. Similarly, a partial solar eclipse can be observed when only a portion of the Moon blocks the Sun and creates a shadow referred to as the penumbra. The penumbra also occurs surrounding the umbra during a total eclipse, effectively covering those regions on the planet that only have a view of a partial eclipse.

Crescents of light from solar eclipse — Crescents of light are projected onto the ground during the partial phases of a solar eclipse due to light from the Sun passing through gaps between the leaves of trees, a pinhole effect. This is a safe and indirect way to view a solar eclipse. Credit: NASA/Johnson Space Center

Solar eclipses happen at least twice per calendar year, with total solar eclipses occurring about once every year and a half. But the possibility of seeing them is rare if you’re not in the right place at the right time. Additionally, since Earth is made up of mostly water, the path of totality, or the area receiving total blockage of the Sun, may not necessarily fall on land.

The year of 2020 sees two solar eclipses. The first occurred on June 21 and was an annular solar eclipse, visible from the continents of Africa and Asia. The second will be a total solar eclipse, occurring on Dec. 14, visible from South America. The path of totality crosses over Chile and Argentina, but some of their areas outside of the path of totality will experience a partial solar eclipse. The total eclipse will also be visible in Antarctica, South Africa, as well as the Pacific, Atlantic, and Indian Oceans. Observers will be able to witness the total solar eclipse for about 2 minutes.

If you are not within the path of totality, watching the total solar eclipse from a virtual location is an option as well. You can view it on NASA TV and the agency’s website, beginning at 10:30 a.m. EST on Dec. 14. Be sure to check it out, as the next total solar eclipse won’t be happening until Dec. 4, 2021.

Top 5 Solar Eclipse Viewing Tips:

Do not stare directly at the Sun. Wear safety approved, protective solar eclipse-viewing glasses to directly view the event or use some indirect means (see below). For more information here are some NASA Safety tips.
To indirectly view the eclipse, create a pinhole camera or box projector. Learn how to build your own here.
Stand under a tree and look at the ground. The trees act as pinhole projectors and will project hundreds of crescent shapes right at your feet.
To capture an eclipse with binoculars, a telescope, or a camera, you must use a safety-approved, protective solar filter on your lens.
Keeping with the theme of 2020 – Observe the eclipse virtually! It will be streamed live here.