The Parker Solar Probe approaches the sun in this artist’s depiction. The probe’s path takes it nearer to the sun than any other human-made object, allowing it to make close-up observations of solar activity.
NASA

The Parker Solar Probe has done the unthinkable. It became the first spacecraft to touch the sun! Scientists reported the announcement on Dec. 14, 2021, at the press conference at the 2021 American Geophysical Union Fall Meeting in New Orleans, Louisiana. The probe was built and operated by the Johns Hopkins Applied Physics Laboratory. The probe flew through the upper atmosphere of the sun, called the corona, to collect samples. The samples will allow scientists to understand more about the sun, just like landing on the moon paved the way for scientists to learn about the moon.

The National Aeronautics and Space Administration (NASA) launched the Parker Solar Probe in 2018. The probe completed its first orbit of the sun in 2019. The probe is the fastest human-made object in the solar system. The sun’s gravity is expected to accelerate the probe to extreme speeds of up to 430,000 miles (700,000 kilometers) per hour. Three years after the launch, the probe has arrived at the sun.

The goals of the mission are 1) to study how energy and heat flow through the corona; 2) to gather information on plasma (the gaslike substance the sun is composed of) and magnetic fields near the sun; and 3) to learn more about how high-energy particles travel outward from the sun.

It uses a set of instruments known as FIELDS, which has antennas to measure electric fields and magnetometers to measure magnetic fields. The probe is also equipped with a pair of cameras to capture images of the sun. The probe carries various instruments for studying particles in the solar wind—that is, the continuous flow of particles from the sun.

The sun’s corona can be as hot as 4,000,000 °F (2,200,000 °C). Because of the corona’s low density (concentration of matter), the Parker Solar Probe will not experience the sun’s most intense heat. However, it will encounter temperatures of up to 2,500 °F (1,377 °C)—hotter than lava from a volcano.

The Parker probe is planned to approach the sun 24 times by the mission’s end. Hopefully, the Parker probe can stand the heat and gather more information about the corona and solar winds.

Winter is the coldest season of the year. The Northern Hemisphere, the northern half of Earth, has winter weather from December to early March. Winter storms produce large snowfalls in some areas, shown here. In the Southern Hemisphere, winter weather begins in late June and lasts until early September.
Art Explosion

Tuesday, Dec. 21, 2021 is the winter solstice for the Northern Hemisphere. On the winter solstice, the sun is at its most southerly position. It marks the day in the year with the least amount of sunlight and the beginning of winter. After the winter solstice, days begin growing longer and nights shorter approaching spring. The winter solstice in the Southern Hemisphere happens in June because the seasons are reversed. December 21 in the Southern Hemisphere is the summer solstice, the longest day of the year.

During the winter solstice, the sun is directly overhead at the Tropic of Capricorn. The Tropic of Capricorn is an imaginary line that traces the southern boundary of the earth’s Tropical Zone. It marks the farthest limit south of the equator where the sun can appear directly overhead. The change results from the tilt of Earth’s axis of rotation. The winter solstice in the Northern Hemisphere happens on December 21 or 22.

Earth spins around its axis once every 24 hours. This motion creates day and night. Earth also travels around the sun once every 365 days. This motion creates the year. The entire solar system revolves around the center of the Milky Way Galaxy.

On the winter solstice which occurs in December in the Northern Hemisphere and June in the Southern Hemisphere, people celebrate the rebirth of the sun and the beginning of winter. For a long time, cultures around the world have celebrated holidays and feasted around the winter solstice. Most of the celebrations feature light since it occurs on the darkest day of the year.

Stonehenge may have been a place where people celebrated the winter solstice. Stonehenge is an ancient ruin in southwestern England. It consists of huge, rough-cut stones set in a circle. The stones are aligned toward the winter solstice sunset. There is archeological evidence the people who lived there held a large feast on the winter solstice.

Ancient Roman holidays were planned around the winter solstice. People have also celebrated specific holidays on the winter solstice in China, Iran, Japan, and Scandinavia. The Incas and some Native American tribes celebrated the winter solstice by fasting, dancing, and then feasting.

September 19, 2018

The sun is the center of our solar system and vital to life on Earth, but there is a lot we do not know about it. On August 12, the United States National Aeronautics and Space Administration (NASA) launched the Parker Solar Probe that will help unravel some of the the sun’s secrets. Over the next few years, the probe will orbit the sun at least 24 times and come blisteringly close to its surface. The probe will reach its first perihelion (the point of an orbit that is closest to the sun) on November 5.

In this NASA illustration, the Parker Solar Probe approaches the sun. The probe launched from Earth on Aug. 12, 2018, and will make its first close pass of the sun on November 5. Credit: NASA/Johns Hopkins APL/Steve Gribben

The Parker Solar Probe is record setting in many ways. It will come within 3.8 million miles (6.1 million kilometers) of the sun, closer than any spacecraft in history. The current record-holder, NASA’s Helios 2, came within 27 million miles (43 million kilometers) of the sun in 1976. (Helios was the god of the sun in Greek mythology.) In comparison, Earth orbits about 93 million miles (150 million kilometers) from the sun, and Mercury, the planet nearest the sun, orbits about 36 million miles (58 million kilometers) away.

The Parker Solar Probe will also be the fastest object ever created by humans—another record it will take from Helios 2—traveling at some 430,000 miles (700,000 kilometers) per hour. Its high speed comes from the huge gravitational pull of the sun. As an object nears the sun, the sun’s gravity accelerates it, much in the way a drain accelerates a circling toy boat.

The probe is also the first to be named after a living person. In 1958, American scientist Eugene Parker hypothesized that ionized atoms were streaming from the sun. He coined the term solar wind for this phenomenon. This explained why a comet’s tail points away from the sun, no matter which direction it is traveling—something that had been observed for centuries but never fully understood. NASA named the groundbreaking probe after Parker to honor his contributions to heliophysics, the study of the sun and its effects on space.

Not far from the sun’s surface, the solar wind speeds up to more than 155 miles (250 kilometers) per second. Scientists are hoping to use the Parker Solar Probe to understand how and why this happens. The probe will dip into the sun’s corona (outer atmosphere) during its closest approaches. Temperatures there reach an unimaginable 4 million °F (2.2 million °C), far hotter than the temperature at the sun’s surface (10,000 °F, or 5,500 °C). Measurements made by the probe will help make sense of this temperature difference.

Getting close to the sun is not easy. The Parker Solar Probe launched from a Delta IV Heavy rocket, one of the most powerful rockets ever built. But it launched in the opposite direction of Earth’s orbit, causing it to slow down in relation to the sun and fall towards it. It will also use the gravity of Venus to slow it down further. At seven different times throughout its mission, it will pass close to Venus, which will act as a brake and hurtle the probe closer to the sun.

Operating close to the sun is also difficult. The Parker Solar Probe is protected by a thick, carbon-composite heat shield that faces the sun at all times. The sun interferes with radio signals at such close range, so the probe must operate without human contact for much of the time. Even getting power is difficult so close to the sun. Of course, solar energy is plentiful, but the scorching temperatures can fry solar cells. Parker’s panels will peek out from behind its heat shield only when the craft is at a safe distance, and they retract as the probe nears the sun.

Improving our knowledge of solar science may help prevent disasters on Earth. Solar events called coronal mass ejections (CME’s) come from the corona and can damage satellites and electrical systems on Earth. Findings from the Parker Solar Probe may help scientists better predict CME’s, allowing officials to temporarily shut down power grids to prevent major damage.

August 22, 2017

Yesterday, on August 21, huge crowds gathered across the United States to watch the solar eclipse within the path of totality, the 70-mile (113-kilometer) wide swath of land from Oregon to South Carolina where the moon completely covered the sun. In Newport, Oregon, throngs of sky watchers greeted the eclipse as it made first landfall at 10:15 a.m. local time. Many thousands of eclipse chasers filled the totality town of Carbondale, Illinois (where the eclipse was longest). Local merchants greeted the tourists with special jewelry, cookies, doughnuts, and other eclipse-themed goods. Across the country, roads toward the path of totality were jammed with traffic and hotels were booked solid—sometimes a year or more in advance of the big event.

This photograph, taken from Northern Cascades National Park in Washington, shows the moon passing before the sun during the solar eclipse of Aug. 21, 2017. Credit: Bill Ingalls, NASA

A total solar eclipse can have a powerful psychological effect on people. Many people, especially in large urban areas, don’t often have reason to look toward the sky in the middle of the day. But, as the moon begins to move over the sun, people could not help but notice the odd darkening of the sky unlike anything they had ever seen. Many people reported feeling a profound sense of awe and a spiritual connection with other people. Others reported a tremendous feeling of unease as the sunlight dimmed and gradually faded completely. But, unlike the experience in ancient times, there were no reports of panic among the masses of eclipse watchers. Astronomers have long been able to precisely predict the time and place of such celestial events. Yesterday, people cheered and applauded the eclipse as they might ooh and aah at a fireworks show, and eclipse glasses (with lenses dark enough to safely view the sun) were passed from hand to hand.

The moon totally blocks the sun during the solar eclipse of Aug. 21, 2017, above Madras, Oregon. Only the sun’s corona is visible around the moon. Credit: Aubrey Gemignani, NASA

At peak totality, the bright disk of the sun was replaced by a dark spot, surrounded by a blazing ring–the sun’s outer atmosphere (called the corona) that is easily visible only during an eclipse. In some regions, people felt a noticeable temperature drop as day briefly turned to night. Stars and planets became visible in the midday sky. Crickets began chirping, thinking night had begun a bit early, and birds roosted and went silent. Some eclipse chasers were surprised and annoyed by mosquitoes, which were fooled into thinking dusk had arrived and went hunting a few hours early.

People gaze skyward wearing eclipse glasses during the solar eclipse of Aug. 21, 2017, on the Oregon State University campus in Corvallis, Oregon. Credit: Mark Floyd, Oregon State University (licensed under CC BY-SA 2.0)

The great solar eclipse of 2017 left the United States just north of Charlotte, South Carolina, at 4:10 p.m. local time. Peak totality ended at 2:49 p.m. at that location. Anyone who missed the eclipse this year will not have to wait long for another chance. The next total solar eclipse visible from a large portion of the United States will occur on April 8, 2024. And Carbondale, Illinois, will once more have a chance to shine. It is the only city that will be in the path of totality in both 2017 and 2024. It’s not too early to start planning!

August 18, 2017

Get ready! On Monday, August 21, if you live in the United States from Oregon to South Carolina, you will be able to experience one of nature’s most impressive sights–a total eclipse of the sun. Across the United States, large crowds are expected in towns, cities, and campsites along the path of totality for the spectacular celestial show. The path of totality is the narrow swath, about 70 miles (110 kilometers) wide, along which the moon will completely blot out the sun.

A solar eclipse occurs when the moon passes between Earth and the sun, blotting out the sun’s light. This photograph shows a total eclipse, in which the moon completely covers the face of the sun. The sun’s outer atmosphere, called the corona, appears as an irregularly shaped halo of light. Credit:

A total solar eclipse occurs when the Earth, sun, and moon are in nearly a straight line and the moon’s shadow sweeps across the face of Earth. The dark moon appears on the edge of the sun and moves slowly across. At the moment of totality, a brilliant halo flashes into view around the darkened sun. This halo is the sun’s outer atmosphere, the corona. The sky remains blue but darkens dramatically. Some bright stars and planets will become visible and the temperature will noticeably drop. After a few minutes, the sun reappears as the moon continues on its orbit. The period when the sun is totally darkened may be as long as 7 minutes 40 seconds, but it averages about 2 1/2 minutes.

A total eclipse of the sun, as shown here, starts at the left. The moon gradually covers the sun, shown photographed through a filter. At the time of the total eclipse, photographed without a filter, the sun’s corona (outer atmosphere) flashes into view. The sun reappears as the moon moves on. Credit: © Atlas Photo Bank/ Photo Researchers

In the United States, the path of totality will cross 14 states: Oregon, Idaho, Wyoming, Montana, Nebraska, Iowa, Kansas, Missouri, Illinois, Kentucky, Tennessee, Georgia, North Carolina, and South Carolina. This will be the first total solar eclipse to cross the United States from coast-to-coast since June 8, 1918, when a total solar eclipse darkened skies from Washington to Florida. The last total solar eclipse to be seen anywhere in the continental United States was in 1979.

Makanda, a village in southern Illinois just south of Carbondale, will see the longest duration of totality for the eclipse–about 2 minutes and 40 seconds. If you miss out, though, don’t worry. Another total solar eclipse will cross the same area in 2024!

If you are going to view the eclipse, be careful! Looking directly at the sun, even during an eclipse, can severely damage your eyes, even if you are wearing sunglasses. If you wish to look directly at the eclipse you will need “eclipse glasses” which have special solar filters. Make sure that your eclipse glasses are undamaged and meet safety standards. Be careful to look away from the sun when you put your eclipse glasses on and take them off. A total solar eclipse can be viewed safely without protection in the path of totality only during the brief time when the disk of the sun is completely hidden.

More on this story next week!

June 21, 2016

When the North Pole has its greatest slant toward the sun, left, summer begins in the Northern Hemisphere and winter begins in the Southern Hemisphere. Credit: WORLD BOOK map

Have you noticed that the days have been getting longer and longer (or the reverse, if you live in the Southern Hemisphere)? The increasing difference between day and night reached its peak yesterday at 22:34 Coordinated Universal Time. This moment is called the June solstice.

A solstice is one of the two moments each year when the sun is at either its northernmost or southernmost position in Earth’s sky. Earth’s axis of rotation is tilted at an angle of 23 degrees 27 minutes in relation to the plane of Earth’s orbit around the sun. As Earth orbits the sun, the angle of tilt points toward the same direction in space. Thus, the direction of this angle in relation to the sun changes throughout the year, causing seasons on Earth.

Solstices mark the beginnings of astronomical summer and winter. In the Northern Hemisphere, the June solstice marks the longest day of the year. In the Southern Hemisphere, yesterday was the shortest day of the year and signaled the arrival of astronomical winter. Now, the day and night will get closer to the same length until the next equinox in September. During an equinox, the tilt of Earth’s axis lies such that neither hemisphere is angled toward the sun. This means that each part of Earth receives the same amount of daylight, so day and night are roughly the same length.

Cultures around the world, but especially those in higher latitudes in the Northern Hemisphere, celebrate the June Solstice. For example, the people of Sweden celebrate Midsummer’s Eve and Midsummer’s Day around the time of the June Solstice. Solstices were also important to ancient people. Thousands of years ago, people living in what is now southwestern England built Stonehenge, a circle of large carved stones. Several features of Stonehenge align with the sun on solstices, suggesting that they were important to its builders.

October 27, 2014

The largest cluster of sunspots in 25 years began hurling its sixth major solar flare in one week at Earth this morning, according to the Space Weather Prediction Center (SWPC), a division of the National Oceanic and Atmospheric Administration. And the cluster shows no signs of slowing down. At this point, it is wider than Jupiter, the largest planet in the solar system, and it is still growing. The cluster is so large, in fact, that it can be seen with the unaided eye when clouds or fog dim the sun. (Warming: Never stare directly at the sun. Even during an eclipse, the sun’s direct rays may damage your eyes.) The sunspot cluster, named AR2192, has caused radio blackouts and other communication disturbances on regions of Earth as they rotate to face the sun.

Sunspots are dark areas on the surface of the sun with high concentrations of magnetic energy. Sunspots appear dark because they are cooler than the rest of the surface. Relatively cooler, that is—only about 7,000 °F (4,000 °C), compared with 11,000 °F (6,000 °C). A solar flare erupts after the twisted magnetic fields of a sunspot suddenly “snap,” releasing billions of tons of solar plasma, a form of matter composed of electrically charged particles. The radiation from the explosion is hurled into space at the speed of light.

Sunspot cluster AR2192 (lower right) is 777,000 miles (125,000 kilometers) wide, nearly as wide as the planet Jupiter. (SDO/HMI)

Luckily, the menacing monster has not—so far—erupted a coronal mass ejection (CME), a ball of plasma larger than a flare. CME’s release enough energy to supply all of Earth’s commercial energy needs for more than 12,000 years. The magnetic storms released by CME’s could seriously disrupt radio and satellite communications, including GPS signals and airline communications, and electric power transmission. Such storms also produce astonishing displays of northern lights that may appear much farther south than normal.

Additional World Book articles:

• Heliosphere
• Solar wind
• Back in Time 2010 (Space exploration)
• Storms from the Sun (A Special Report)

July 13, 2012

For nearly 100 years, scientists have known that the Andromeda Galaxy, our nearest galactic neighbor, was heading our way. But they didn’t know whether an encounter would be a glancing blow or a head-on collision or if Andromeda would miss our Milky Way altogether. Now, thanks to measurements made using the Hubble Space Telescope, scientists with the Space Telescope Science Institute in Baltimore have calculated that Andromeda, which is hurtling toward us at a speed of about 250,000 miles (400,000 kilometers) per hour, will plow directly into the Milky Way in about 4 billion years. The encounter will produce some dramatic changes, the scientists said. But the destruction of the sun and the solar system will not be one of them.

The Milky Way, our "home" galaxy, is a spiral galaxy. Astronomers believe that after neighboring galaxy Andromeda--also a spiral galaxy--smashes into the Milky Way, the two will form an elliptical galaxy. (Artwork © Jon Lomberg and the National Air and Space Museum)

As Andromeda gets closer, it will fill more and more of our night sky. Eventually, the two spiral galaxies will begin to merge. A blaze of new stars will appear in the sky as clouds of dust and gas are compressed by the gravitational forces tearing at the galaxies. Stars within galaxies are so far apart that the sun or planets will not collide with other space bodies. But scientists think the solar system will be flung into a different part of the Milky Way, probably even farther from the galactic core than it is today. Over the next 2 billion years, the two spiral galaxies will combine to form an elliptical galaxy that some scientists are calling “Milkomeda.”

Earth and the sun will probably not be around to witness the final product, however. Scientists have estimated that about 5 billion years from now, the sun will have used up its hydrogen fuel. Eventually, it will expand enormously, probably nearly to the current orbit of Mercury, and swallow Earth.

Additional World Book articles:

•  Galaxy
• The Formation of Galaxies and Other Structures  (a Special Report)

March 8, 2012

A massive wave of radiation from the sun–the most intense since 2006–is walloping Earth today, according to the Space Weather Prediction Center (SWPC), a division of the National Oceanic and Atmospheric Administration (NOAA). This ball of plasma and charged particles, called a coronal mass ejection (CME), is causing the second major magnetic storm in Earth’s magnetic field this week. The latest solar outburst originated in a monster solar flare that erupted from the surface of the sun on Tuesday, March 6. Several NASA satellites videoed the flare as it hurled the CME toward Earth. Traveling through space at 4 million miles (6.4 million kilometers) per hour, the CME first hit Earth shortly after midnight. Fortunately, the eruption sideswiped Earth rather than hitting it head-on.

CME’s are the strongest type of solar eruptions, releasing enough energy to supply all of Earth’s commercial energy needs for more than 12,000 years. The magnetic storms they cause have the potential to seriously disrupt radio and satellite communications, including GPS signals and airline communications, and electric power transmission. The charged particles also may produce displays of the northern lights much farther south than normal. Authorities said the effects of the current storm could last for 24 hours. The CME was not expected to affect the health of people on Earth’s surface.

The sun blazes with energy. On its surface, magnetic forces create loops and streams of gas that extend tens of thousands of miles or kilometers into space. This image was made by photographing ultraviolet radiation given off by atoms of iron gas that are hotter than 9 million °F (5 million °C). NASA/Transition Region & Coronal Explorer

On Sunday, March 4, another flare–the most powerful of 2012 so far–erupted from the same sunspot. That CME hit Earth’s magnetic field on the night of Wednesday, March 7. Radiation from that storm was still creating turbulence in Earth’s magnetic field when the second storm arrived. The sun is currently entering a more active phase, after several years of quiet. Solar activity varies over a period of about 11 years. The current cycle is expected to reach its peak in 2013.

Additional World Book articles:

• Heliosphere
• Solar wind
• Back in Time 2010 (Space exploration)
• Storms from the Sun (A Special Report)

Dec. 12, 2011

People seeking evidence of extraterrestrial life got a jolt in early December when images from space probes studying the sun appeared to show a mysterious object parked in the orbit of the planet Mercury. Rumors of aliens observing Earth from a “cloaked” spaceship went viral on the Internet. Like Harry Potter’s invisibility cloak, cloaking devices render objects invisible. One of most famous cloaking device in modern science fiction was that used by the Klingons in the Star Trek series to ambush the U.S.S. Enterprise and other ships of the United Federation of Planets.

The images were from the Solar Terrestrial Relations Observatory (STEREO), a pair of satellites designed to help scientists predict spectacular eruptions from the sun called coronal mass ejections (CME’s). The satellites follow Earth’s orbit around the sun, with one traveling 37 million miles (60 million kilometers) ahead of Earth and the other following 37 million miles behind. In the series of three-dimensional images, the probes showed a CME washing over Mercury. But the images also seemed to show another object nearby. The object was invisible, but as the CME passed over it, the dark shape of a cylinder was revealed. Were we no longer alone in the universe?

A drawing of one of the STEREO spacecrafts is superimposed on an actual image of a coronal mass ejection from May 20, 2011, taken by the probe. NASA

In the end, the scientists who process the STEREO data had a logical explanation. It seems that the computers that filter the blinding light of the sun from the STEREO images also mistakenly removed some of the CME itself. The black spot in the images was only the result of an overactive computer program. The finding allowed the United States government to maintain its position on the existence of life on other planets. In November 2011, the White House Office of Science and Technology Policy had issued an official statement that the U.S. government had no knowledge that extraterrestrial life exists or that beings from other planets have made contact with humans.

Additional World Book articles:

• Life (The search for life on other planets)
• SETI Institute
• Storms from the Sun (a Special Report)