Tag Archives: Heliophysics

NASA Space Place – The Shape Of The Solar System

Poster’s Note: One of the many under-appreciated aspects of NASA is the extent to which it publishes quality science content for children and Ph.D.’s alike. NASA Space Place has been providing general audience articles for quite some time that are freely available for download and republishing. Your tax dollars help promote science! The following article was provided for reprinting in June, 2017.

By Marcus Woo

2013february2_spaceplaceWhen Stamatios (Tom) Krimigis was selected for the Voyager mission in 1971, he became the team’s youngest principal investigator of an instrument, responsible for the Low Energy Charged Particles (LECP) instrument. It would measure the ions coursing around and between the planets, as well as those beyond. Little did he know, though, that more than 40 years later, both Voyager 1 and 2 still would be speeding through space, continuing to literally reshape our view of the solar system.

The solar system is enclosed in a vast bubble, carved out by the solar wind blowing against the gas of the interstellar medium. For more than half a century, scientists thought that as the sun moved through the galaxy, the interstellar medium would push back on the heliosphere, elongating the bubble and giving it a pointy, comet-like tail similar to the magnetospheres—bubbles formed by magnetic fields—surrounding Earth and most of the other planets

“We in the heliophysics community have lived with this picture for 55 years,” said Krimigis, of The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. “And we did that because we didn’t have any data. It was all theory.”

But now, he and his colleagues have the data. New measurements from Voyager and the Cassini spacecraft suggest that the bubble isn’t pointy after all. It’s spherical.

Their analysis relies on measuring high-speed particles from the heliosphere boundary. There, the heated ions from the solar wind can strike neutral atoms coming from the interstellar medium and snatch away an electron. Those ions become neutral atoms, and ricochet back toward the sun and the planets, uninhibited by the interplanetary magnetic field.

Voyager is now at the edge of the heliosphere, where its LECP instrument can detect those solar-wind ions. The researchers found that the number of measured ions rise and fall with increased and decreased solar activity, matching the 11-year solar cycle, showing that the particles are indeed originating from the sun.

Meanwhile, Cassini, which launched 20 years after Voyager in 1997, has been measuring those neutral atoms bouncing back, using another instrument led by Krimigis, the Magnetosphere Imaging Instrument (MIMI). Between 2003 and 2014, the number of measured atoms soared and dropped in the same way as the ions, revealing that the latter begat the former. The neutral atoms must therefore come from the edge of the heliosphere.

If the heliosphere were comet-shaped, atoms from the tail would take longer to arrive at MIMI than those from the head. But the measurements from MIMI, which can detect incoming atoms from all directions, were the same everywhere. This suggests the distance to the heliosphere is the same every which way. The heliosphere, then, must be round, upending most scientists’ prior assumptions.

It’s a discovery more than four decades in the making. As Cassini ends its mission this year, the Voyager spacecraft will continue blazing through interstellar space, their remarkable longevity having been essential for revealing the heliosphere’s shape.

“Without them,” Krimigis says, “we wouldn’t be able to do any of this.”

To teach kids about the Voyager mission, visit the NASA Space Place: spaceplace.nasa.gov/voyager-to-planets

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Caption: New data from NASA’s Cassini and Voyager show that the heliosphere — the bubble of the sun’s magnetic influence that surrounds the solar system — may be much more compact and rounded than previously thought. The image on the left shows a compact model of the heliosphere, supported by this latest data, while the image on the right shows an alternate model with an extended tail. The main difference is the new model’s lack of a trailing, comet-like tail on one side of the heliosphere. This tail is shown in the old model in light blue. Image credits: Dialynas, et al. (left); NASA (right)

About NASA Space Place

With articles, activities, crafts, games, and lesson plans, NASA Space Place encourages everyone to get excited about science and technology. Visit spaceplace.nasa.gov (facebook|twitter) to explore space and Earth science!

NASA Space Place – Solar Wind Creates — And Whips — A Magnetic Tail Around Earth

Poster’s Note: One of the many under-appreciated aspects of NASA is the extent to which it publishes quality science content for children and Ph.D.’s alike. NASA Space Place has been providing general audience articles for quite some time that are freely available for download and republishing. Your tax dollars help promote science! The following article was provided for reprinting in August, 2015.

By Dr. Ethan Siegel

2013february2_spaceplaceAs Earth spins on its axis, our planet’s interior spins as well. Deep inside our world, Earth’s metal-rich core produces a magnetic field that spans the entire globe, with the magnetic poles offset only slightly from our rotational axis. If you fly up to great distances, well above Earth’s surface, you’ll find that this magnetic web, called the magnetosphere, is no longer spherical. It not only bends away from the direction of the sun at high altitudes, but it exhibits some very strange features, all thanks to the effects of our parent star.

The sun isn’t just the primary source of light and heat for our world; it also emits an intense stream of charged particles, the solar wind, and has its own intense magnetic field that extends much farther into space than our own planet’s does. The solar wind travels fast, making the 150 million km (93 million mile) journey to our world in around three days, and is greatly affected by Earth. Under normal circumstances, our world’s magnetic field acts like a shield for these particles, bending them out of the way of our planet and protecting plant and animal life from this harmful radiation.

But for every action, there’s an equal and opposite reaction: as our magnetosphere bends the solar wind’s ions, these particles also distort our magnetosphere, creating a long magnetotail that not only flattens and narrows, but whips back-and-forth in the onrushing solar wind. The particles are so diffuse that collisions between them practically never occur, but the electromagnetic interactions create waves in Earth’s magnetosphere, which grow in magnitude and then transfer energy to other particles. The charged particles travel within the magnetic field toward both poles, and when they hit the ionosphere region of Earth’s upper atmosphere, they collide with ions of oxygen and nitrogen causing aurora. Missions such as the European Space Agency and NASA Cluster mission have just led to the first accurate model and understanding of equatorial magnetosonic waves, one such example of the interactions that cause Earth’s magnetotail to whip around in the wind like so.

The shape of Earth’s magnetic field not only affects aurorae, but can also impact satellite electronics. Understanding its shape and how the magnetosphere interacts with the solar wind can also lead to more accurate predictions of energetic electrons in near-Earth space that can disrupt our technological infrastructure. As our knowledge increases, we may someday be able to reach one of the holy grails of connecting heliophysics to Earth: forecasting and accurately predicting space weather and its effects. Thanks to the Cluster Inner Magnetosphere Campaign, Van Allen Probes, Mars Odyssey Thermal Emission Imaging System, Magnetospheric Multiscale, and Heliophysics System Observatory missions, we’re closer to this than ever before.

Kids can learn about how solar wind defines the edges of our solar system at NASA Space Place – spaceplace.nasa.gov/interstellar


Caption: Composite of 25 images of the sun, showing solar outburst/activity over a 365 day period; NASA / Solar Dynamics Observatory / Atmospheric Imaging Assembly / S. Wiessinger; post-processing by E. Siegel.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

About NASA Space Place

The goal of the NASA Space Place is “to inform, inspire, and involve children in the excitement of science, technology, and space exploration.” More information is available at their website: http://spaceplace.nasa.gov/

NASA News Digest: Space Science For 12 October – 16 October 2014

Greetings fellow astrophiles,

The NASA News service provides up-to-date announcements of NASA policy, news events, and space science. A recent selection of space science articles are provided below, including direct links to the full announcements. Those interested in receiving these news announcements directly from NASA can subscribe to their service by sending an email to:


NASA Mission Finds Widespread Evidence of Young Lunar Volcanism

RELEASE 14-284 (Click here for the full article) – 12 October 2014

2014oct20_14_284NASA’s Lunar Reconnaissance Orbiter (LRO) has provided researchers strong evidence the moon’s volcanic activity slowed gradually instead of stopping abruptly a billion years ago.

Scores of distinctive rock deposits observed by LRO are estimated to be less than 100 million years old. This time period corresponds to Earth’s Cretaceous period, the heyday of dinosaurs. Some areas may be less than 50 million years old. Details of the study are published online in Sunday’s edition of Nature Geoscience.

“This finding is the kind of science that is literally going to make geologists rewrite the textbooks about the moon,” said John Keller, LRO project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

To access the complete collection of LROC images, visit: lroc.sese.asu.edu/

For more information about LRO, visit: www.nasa.gov/lro

NASA Mission Provides Its First Look at Martian Upper Atmosphere

RELEASE 14-285 (Click here for the full article) – 14 October 2014

2014oct20_14_285NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft has provided scientists their first look at a storm of energetic solar particles at Mars, produced unprecedented ultraviolet images of the tenuous oxygen, hydrogen, and carbon coronas surrounding the Red Planet, and yielded a comprehensive map of highly-variable ozone in the atmosphere underlying the coronas.

The spacecraft, which entered Mars’ orbit Sept. 21, now is lowering its orbit and testing its instruments. MAVEN was launched to Mars in November 2013, to help solve the mystery of how the Red Planet lost most of its atmosphere.

“All the instruments are showing data quality that is better than anticipated at this early stage of the mission,” said Bruce Jakosky, MAVEN Principal Investigator at the University of Colorado, Boulder. “All instruments have now been turned on — although not yet fully checked out — and are functioning nominally. It’s turning out to be an easy and straightforward spacecraft to fly, at least so far. It really looks as if we’re headed for an exciting science mission.”

For more about MAVEN, visit: www.nasa.gov/maven

NASA’s Hubble Telescope Finds Potential Kuiper Belt Targets for New Horizons Pluto Mission

RELEASE 14-281 (Click here for the full article) – 15 October 2014

2014oct20_14_281Peering out to the dim, outer reaches of our solar system, NASA’s Hubble Space Telescope has uncovered three Kuiper Belt objects (KBOs) the agency’s New Horizons spacecraft could potentially visit after it flies by Pluto in July 2015.

The KBOs were detected through a dedicated Hubble observing program by a New Horizons search team that was awarded telescope time for this purpose.

“This has been a very challenging search and it’s great that in the end Hubble could accomplish a detection – one NASA mission helping another,” said Alan Stern of the Southwest Research Institute (SwRI) in Boulder, Colorado, principal investigator of the New Horizons mission.

The Kuiper Belt is a vast rim of primordial debris encircling our solar system. KBOs belong to a unique class of solar system objects that has never been visited by spacecraft and which contain clues to the origin of our solar system.

For images of the KBOs and more information about Hubble, visit: www.nasa.gov/hubble

For information about the New Horizons mission, visit: www.nasa.gov/newhorizons

NASA’s Hubble Finds Extremely Distant Galaxy through Cosmic Magnifying Glass

RELEASE 14-283 (Click here for the full article) – 16 October 2014

2014oct20_14_283Peering through a giant cosmic magnifying glass, NASA’s Hubble Space Telescope has spotted a tiny, faint galaxy — one of the farthest galaxies ever seen. The diminutive object is estimated to be more than 13 billion light-years away.

This galaxy offers a peek back to the very early formative years of the universe and may just be the tip of the iceberg.

“This galaxy is an example of what is suspected to be an abundant, underlying population of extremely small, faint objects that existed about 500 million years after the big bang, the beginning of the universe,” explained study leader Adi Zitrin of the California Institute of Technology in Pasadena, California. “The discovery is telling us galaxies as faint as this one exist, and we should continue looking for them and even fainter objects, so that we can understand how galaxies and the universe have evolved over time.”

For images and more information about Hubble, visit: www.nasa.gov/hubble

NASA Spacecraft Provides New Information About Sun’s Atmosphere

RELEASE 14-288 (Click here for the full article) – 16 Ocrober 2014

2014oct20_14_288NASA’s Interface Region Imaging Spectrograph (IRIS) has provided scientists with five new findings into how the sun’s atmosphere, or corona, is heated far hotter than its surface, what causes the sun’s constant outflow of particles called the solar wind, and what mechanisms accelerate particles that power solar flares.

The new information will help researchers better understand how our nearest star transfers energy through its atmosphere and track the dynamic solar activity that can impact technological infrastructure in space and on Earth. Details of the findings appear in the current edition of Science.

“These findings reveal a region of the sun more complicated than previously thought,” said Jeff Newmark, interim director for the Heliophysics Division at NASA Headquarters in Washington. “Combining IRIS data with observations from other Heliophysics missions is enabling breakthroughs in our understanding of the sun and its interactions with the solar system.”

For more information about IRIS, visit: www.nasa.gov/iris