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Eclipse-maker: How Proba-3 subtracts the Sun
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By NASA
This article is for students grades 5-8.
The Sun is the star of our solar system. Its gravity holds Earth and our planetary neighbors in its orbit. At 865,000 miles (1.4 million km) in diameter, it’s the largest object in our solar system. On Earth, its influence is felt in our weather, seasons, climate, and more. Let’s learn about our dynamic star and its connections to life on Earth.
What is the Sun, and what is it made of?
The Sun is a yellow dwarf star. It is approximately 4.5 billion years old and is in its “main sequence” phase. This means it is partway through its lifecycle with a few billion more years ahead of it.
The Sun is made of hydrogen and helium gases. At its core, hydrogen is fused to form helium. This nuclear reaction creates the Sun’s heat and light. That energy moves outward through the Sun’s radiative zone and convective zone. It then reaches the Sun’s visible surface and lower atmosphere, called the photosphere. Above the photosphere lies the chromosphere, which forms the Sun’s middle atmosphere, and beyond that is the corona, the Sun’s outermost atmosphere.
The Sun is a yellow dwarf star with a complex series of layers and features.NASA What is the solar cycle?
The Sun goes through a pattern of magnetic activity known as the solar cycle. During each cycle, the Sun experiences a very active period called “solar maximum” and a less active period called “solar minimum.”
During solar maximum, increased magnetic activity creates sunspots. These appear as darker, cooler spots on the Sun’s surface. The more sunspots we can see, the more active the Sun is.
The solar cycle begins at solar minimum, peaks at solar maximum, and then returns to solar minimum. This cycle is driven by the Sun’s magnetic polarity, which flips – north becomes south, and vice versa – every 11 years. It takes two cycles – or 22 years – to complete the full magnetic cycle where the poles return to their original positions.
The Sun’s level of magnetic activity changes throughout its 11-year solar cycle. During each cycle, the Sun experiences a less-active period called “solar minimum” (left) and a very active period called “solar maximum” (right).NASA Wait. The Sun’s magnetic poles can flip??
Yes! Like Earth, the Sun has north and south magnetic poles. But unlike Earth, the Sun’s poles flip regularly. Each 11-year solar cycle is marked by the flipping of the Sun’s poles. The increased magnetic activity during solar maximum makes the north and south poles less defined. As the cycle moves back to solar minimum, the polarization of the poles returns – with flipped polarity.
Unlike Earth, the Sun’s poles regularly flip with each 11-year solar cycle.NASA What is space weather?
Space weather includes phenomena such as solar wind, solar storms, and solar flares. When space weather conditions are calm, there may be little noticeable effect on Earth. But when the Sun is more active, space weather has real impacts on Earth and in space.
Let’s explore these phenomena and how they affect our planet.
Periods of increased solar activity can cause noticeable effects on Earth and in space.NASA What is solar wind?
Solar wind is a stream of charged particles that flow outward from the Sun’s corona. It extends far beyond the orbit of the planets in our solar system. When solar wind reaches Earth, its charged particles interact with Earth’s magnetic field. This causes colorful streams of moving light at Earth’s north and south poles called aurora.
Earth’s magnetic field protects our planet from the charged solar particles of the solar wind.NASA What are solar storms, solar flares, and coronal mass ejections?
The Sun’s magnetic fields are a tangle of constant motion. These fields twist and stretch to the point that they snap and reconnect. When this magnetic reconnection occurs, it releases a burst of energy that can cause a solar storm.
Solar storms can include phenomena such as solar flares or coronal mass ejections. They happen more frequently around the solar maximum of the Sun’s cycle. A solar flare is an intense burst of light and energy from the Sun’s surface. Solar flares tend to happen near sunspots where the Sun’s magnetic fields are strongest. A coronal mass ejection is a massive cloud of material flowing outward from the Sun. These can occur on their own or along with solar flares.
The Sun’s magnetic field is strongest near sunspots. These active regions of the Sun’s surface release energy in the form of solar flares and coronal mass ejections like these.NASA How do these phenomena affect Earth?
When a solar storm erupts towards Earth, our atmosphere and magnetic field protect us from significant harm. However, some impacts are possible, both on Earth and in space. For example, strong solar storms can cause power outages and radio blackouts. GPS signals can be disrupted. Satellite electronics can be affected. And astronauts working outside of the International Space Station could be exposed to dangerous radiation. NASA monitors and forecasts space weather to protect the safety and health of astronauts and spacecraft.
When charged particles from intense solar storms interact with Earth’s magnetic fields, colorful auroras like this one captured in Saskatchewan, Canada, can occur.NASA Learn more about the Sun
NASA’s Parker Solar Probe launched in 2018 on the first-ever mission to fly into the Sun’s corona. Since its first pass through the corona in 2021, every orbit has brought it closer to the Sun. On Dec. 24, 2024, it makes the first of its three final, closest solar approaches of its primary mission. Test your knowledge with NASA’s new quiz, Kahoot! Parker Solar Probe trivia.
Visit these resources for more details about the Sun:
https://science.nasa.gov/sun/facts/ https://spaceplace.nasa.gov/all-about-the-sun/en/ https://science.nasa.gov/exoplanets/stars/ Explore More For Students Grades 5-8 View the full article
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
On Dec. 10, 1974, NASA launched Helios 1, the first of two spacecraft to make close observations of the Sun. In one of the largest international efforts at the time, the Federal Republic of Germany, also known as West Germany, provided the spacecraft, NASA’s Goddard Space Flight Center in Greenbelt, Maryland, had overall responsibility for U.S. participation, and NASA’s Lewis, now Glenn, Research Center in Cleveland provided the launch vehicle. Equipped with 10 instruments, Helios 1 made its first close approach to the Sun on March 15, 1975, passing closer and traveling faster than any previous spacecraft. Helios 2, launched in 1976, passed even closer. Both spacecraft far exceeded their 18-month expected lifetime, returning unprecedented data from their unique vantage points.
The fully assembled Helios 1 spacecraft prepared for launch.Credit: NASA The West German company Messerchmitt-Bölkow-Blohm built the two Helios probes, the first non-Soviet and non-American spacecraft placed in heliocentric orbit, for the West German space agency DFVLR, today’s DLR. Each 815-pound Helios probe carried 10 U.S. and West German instruments, weighing a total of 158 pounds, to study the Sun and its environment. The instruments included high-energy particle detectors to measure the solar wind, magnetometers to study the Sun’s magnetic field and variations in electric and magnetic waves, and micrometeoroid detectors. Once activated and checked out, operators in the German control center near Munich controlled the spacecraft and collected the raw data. To evenly distribute the solar radiation the spacecraft spun on its axis once every second, and optical mirrors on its surface reflected the majority of the heat.
Workers encapsulate a Helios solar probe into its payload fairing. Credit: NASA
Launch of Helios 1 took place at 2:11 a.m. EST Dec. 10, 1974, from Launch Complex 41 at Cape Canaveral Air Force, now Space Force, Station, on a Titan IIIE-Centaur rocket. This marked the first successful flight of this rocket, at the time the most powerful in the world, following the failure of the Centaur upper stage during the rocket’s inaugural launch on Feb. 11, 1974. The successful launch of Helios 1 provided confidence in the Titan IIIE-Centaur, needed to launch the Viking orbiters and landers to Mars in 1976 and the Mariner Jupiter-Saturn, later renamed Voyager, spacecraft in 1977 to begin their journeys through the outer solar system. The Centaur upper stage placed Helios 1 into a solar orbit with a period of 190 days, with its perihelion, or closest point to the Sun, well inside the orbit of Mercury. Engineers activated the spacecraft’s 10 instruments within a few days of launch, with the vehicle declared fully operational on Jan. 16, 1975. On March 15, Helios 1 reached its closest distance to the Sun of 28.9 million miles, closer than any other previous spacecraft – Mariner 10 held the previous record during its three Mercury encounters. Helios 1 also set a spacecraft speed record, traveling at 148,000 miles per hour at perihelion. Parts of the spacecraft reached a temperature of 261 degrees Fahrenheit, but the instruments continued to operate without problems. During its second perihelion on Sept. 21, temperatures reached 270 degrees, affecting the operation of some instruments. Helios 1 continued to operate and return useful data until both its primary and backup receivers failed and its high-gain antenna no longer pointed at Earth. Ground controllers deactivated the spacecraft on Feb. 18, 1985, with the last contact made on Feb. 10, 1986.
Helios 1 sits atop its Titan IIIE-Centaur rocket at Launch Complex 41 at Cape Canaveral Air Force, now Space Force, Station in Florida.Credit: NASA
Helios 2 launched on Jan. 15, 1976, and followed a path similar to its predecessor’s but one that took it even closer to the Sun. On April 17, it approached to within 27 million miles of Sun, traveling at a new record of 150,000 miles per hour. At that distance, the spacecraft experienced 10% more solar heat than its predecessor. Helios 2’s downlink transmitter failed on March 3, 1980, resulting in no further useable data from the spacecraft. Controllers shut it down on Jan. 7, 1981. Scientists correlated data from the Helios instruments with similar data gathered by other spacecraft, such as the Interplanetary Monitoring Platform Explorers 47 and 50 in Earth orbit, the Pioneer solar orbiters, and Pioneer 10 and 11 in the outer solar system. In addition to their solar observations, Helios 1 and 2 studied the dust and ion tails of the comets C/1975V1 West, C/1978H1 Meier, and C/1979Y1 Bradfield. The information from the Helios probes greatly increased our knowledge of the Sun and its environment, and also raised more questions left for later spacecraft from unique vantage points to try to answer.
llustration of a Helios probe in flight, with all its booms deployed. Credit: NASA The joint ESA/NASA Ulysses mission studied the Sun from vantage points above its poles. After launch from space shuttle Discovery during STS-41 on Oct. 6, 1990, Ulysses used Jupiter’s gravity to swing it out of the ecliptic plane and fly first over the Sun’s south polar region from June to November 1994, then over the north polar region from June and September 1995. Ulysses continued its unique studies during several more polar passes until June 30, 2009, nearly 19 years after launch and more than four times its expected lifetime. NASA’s Parker Solar Probe, launched on Aug. 12, 2018, has made ever increasingly close passes to the Sun, including flying through its corona, breaking the distance record set by Helios 2. The Parker Solar Probe reached its first perihelion of 15 million miles on Nov. 5, 2018, with its closest approach of just 3.86 million miles of the Sun’s surface, just 4.5 percent of the Sun-Earth distance, planned for Dec. 24, 2024. The ESA Solar Orbiter launched on Feb. 10, 2020, and began science operations in November 2021. Its 10 instruments include cameras that have returned the highest resolution images of the Sun including its polar regions from as close as 26 million miles away.
Illustration of the Ulysses spacecraft over the Sun’s pole.Credit: NASA Illustration of the Parker Solar Probe during a close approach to the Sun.Credit: NASA The ESA Solar Orbiter observing the Sun.Credit: NASA About the Author
John J. Uri
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Last Updated Dec 10, 2024 Related Terms
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By European Space Agency
Video: 00:09:01 Proba-3 is such an ambitious mission that it needs more than one single spacecraft to succeed. In order for Proba-3’s Coronagraph spacecraft to observe the Sun’s faint surrounding atmosphere, its disk-bearing Occulter spacecraft must block out the fiery solar disk. This means Proba-3’s Occulter ends up facing the Sun continuously, making it a valuable platform for science in its own right.
Proba-3 is scheduled for launch on a PSLV-XL rocket from Satish Dhawan Space Centre in Sriharikota, India, on Wednesday, 4 December, at 11:38 CET (10:38 GMT, 16:08 local time).
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By NASA
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
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A 3D simulation showing the evolution of turbulent flows in the upper layers of the Sun. The more saturated and bright reds represent the most vigorous upward or downward twisting motions. Clear areas represent areas where there is only relatively slow up-flows, with very little twisting.NASA/Irina Kitiashvili and Timothy A. Sandstrom NASA supercomputers are shedding light on what causes some of the Sun’s most complex behaviors. Using data from the suite of active Sun-watching spacecraft currently observing the star at the heart of our solar system, researchers can explore solar dynamics like never before.
The animation shows the strength of the turbulent motions of the Sun’s inner layers as materials twist into its atmosphere, resembling a roiling pot of boiling water or a flurry of schooling fish sending material bubbling up to the surface or diving it further down below.
“Our simulations use what we call a realistic approach, which means we include as much as we know to-date about solar plasma to reproduce different phenomena observed with NASA space missions,” said Irina Kitiashvili, a scientist at NASA’s Ames Research Center in California’s Silicon Valley who helped lead the study.
Using modern computational capabilities, the team was able, for the first time to reproduce the fine structures of the subsurface layer observed with NASA’s Solar Dynamics Observatory.
“Right now, we don’t have the computational capabilities to create realistic global models of the entire Sun due to the complexity,” said Kitiashvili. “Therefore, we create models of smaller areas or layers, which can show us structures of the solar surface and atmosphere – like shock waves or tornado-like features measuring only a few miles in size; that’s much finer detail than any one spacecraft can resolve.”
Scientists seek to better understand the Sun and what phenomena drive the patterns of its activity. The connection and interactions between the Sun and Earth drive the seasons, ocean currents, weather, climate, radiation belts, auroras and many other phenomena. Space weather predictions are critical for exploration of space, supporting the spacecraft and astronauts of NASA’s Artemis campaign. Surveying this space environment is a vital part of understanding and mitigating astronaut exposure to space radiation and keeping our spacecraft and instruments safe.
This has been a big year for our special star, studded with events like the annular eclipse, a total eclipse, and the Sun reaching its solar maximum period. In December 2024, NASA’s Parker Solar Probe mission – which is helping researchers to understand space weather right at the source – will make its closest-ever approach to the Sun and beat its own record of being the closest human-made object to reach the Sun.
The Sun keeps surprising us. We are looking forward to seeing what kind of exciting events will be organized by the Sun."
Irina Kitiashvili
NASA Scientist
“The Sun keeps surprising us,” said Kitiashvili. “We are looking forward to seeing what kind of exciting events will be organized by the Sun.”
These simulations were run on the Pleaides supercomputer at the NASA Advanced Supercomputing facility at NASA Ames over several weeks of runtime, generating terabytes of data.
NASA is showcasing 29 of the agency’s computational achievements at SC24, the international supercomputing conference, Nov. 17-22, 2023, in Atlanta, Georgia. For more technical information, visit:
https://www.nas.nasa.gov/sc24
For news media: Members of the news media interested in covering this topic should reach out to the NASA Ames newsroom.
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Last Updated Nov 21, 2024 Related Terms
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