Sentinels of the Heliosphere
- Visualizations by:
- Greg Shirah
- View full credits
As a society dependent on technology, both in everyday life, and as part of our economic growth, space weather becomes increasingly important. Changes in space weather, either by solar events or geomagnetic events, can disrupt and even damage power grids and satellite communications. Space weather events can also generate x-rays and gamma-rays, as well as particle radiations, that can jeopardize the lives of astronauts living and working in space.
This visualization tours the regions of near-Earth orbit; the Earth's magnetosphere, sometimes called geospace; the region between the Earth and the Sun; and finally out beyond Pluto, where Voyager 1 and 2 are exploring the boundary between the Sun and the rest of our Milky Way galaxy. Along the way, we see these regions patrolled by a fleet of satellites that make up NASA's Heliophysics Observatory Telescopes. Many of these spacecraft do not take images in the conventional sense but record fields, particle energies and fluxes in situ. Many of these missions are operated in conjunction with international partners, such as the European Space Agency (ESA) and the Japanese Space Agency (JAXA).
The Earth and distances are to scale. Larger objects are used to represent the satellites and other planets for clarity.
Here are the spacecraft featured in this movie:
Near-Earth Fleet:
- Hinode: Observes the Sun in multiple wavelengths up to x-rays. SVS page
- RHESSI : Observes the Sun in x-rays and gamma-rays. SVS page
- TRACE: Observes the Sun in visible and ultraviolet wavelengths. SVS page
- TIMED: Studies the upper layers (40-110 miles up) of the Earth's atmosphere.
- FAST: Measures particles and fields in regions where aurora form.
- CINDI: Measures interactions of neutral and charged particles in the ionosphere.
- AIM: Images and measures noctilucent clouds. SVS page
Geospace Fleet:
- Geotail: Conducts measurements of electrons and ions in the Earth's magnetotail.
- Cluster: This is a group of four satellites which fly in formation to measure how particles and fields in the magnetosphere vary in space and time. SVS page
- THEMIS: This is a fleet of five satellites to study how magnetospheric instabilities produce substorms. SVS page
L1 Fleet:
The L1 point is a Lagrange Point, a point between the Earth and the Sun where the gravitational pull is approximately equal. Spacecraft can orbit this location for continuous coverage of the Sun.- SOHO: Studies the Sun with cameras and a multitude of other instruments. SVS page
- ACE: Measures the composition and characteristics of the solar wind.
- Wind: Measures particle flows and fields in the solar wind.
Heliospheric Fleet
- STEREO-A and B: These two satellites observe the Sun, with imagers and particle detectors, off the Earth-Sun line, providing a 3-D view of solar activity. SVS page
Heliopause Fleet
- Voyager 1 and 2: These spacecraft conducted the original 'Planetary Grand Tour' of the solar system in the 1970s and 1980s. They have now travelled further than any human-built spacecraft and are still returning measurements of the interplanetary medium. SVS page
This enhanced, narrated visualization was shown at the SIGGRAPH 2009 Computer Animation Festival in New Orleans, LA in August 2009; an eariler version created for AGU was called NASA's Heliophysics Observatories Study the Sun and Geospace.
This movie shows the orbits of the fleet of NASA spacecraft exploring the heliosphere.
For complete transcript, click here.
This video is also available on our YouTube channel.

As we approach the Earth, we get a wide view of the spacecraft located at L1 as well as the Earth nestled within the magnetosphere. The magnetosphere forms due to the interaction of the Earth's geomagnetic field with the plasma of the solar wind. Solar wind pressure drags the magnetosphere back from the Earth, away from the Sun, much like a 'wind sock'. For convenience, arrows remind us of the direction of the Sun (yellow) and the direction that the Earth travels along its orbit (blue).

We fly throught the boundary of the magnetosphere for a closeup view of the Earth (note that the clouds are changing, updating based on weather satellite imagery from this time). We also see the orbits of heliofleet satellites that occupy near-Earth orbit. Here, the fleet include not only Earth-observing missions like TIMED and FAST, but solar observatories as well: TRACE, RHESSI, and Hinode.

The spacecraft STEREO-A and B make their first lunar flyby, using the Moon for a gravity-assist. For STEREO-A, the flyby transfers enough momentum to send the satellite into a solar orbit, slightly closer to the Sun than the Earth. From this orbit, STEREO-A becomes STEREO-Ahead as it begins to move ahead relative to the Earth in its orbit.

Now we take a spin around the L1 point, observing SOHO, ACE, and Wind as they execute their trajectories around this location. Because L1 is actually an unstable point, the spacecraft need occasional trim maneuvers to maintain their location. We speed up time as we orbit, also noting that the L1 point seems to execute small oscillations in the yellow Earth-Sun marker. These oscillations are due to the gravitational tug of the Moon as it orbits the Earth. After spending over a year at L1, we return to the Earth to see what is new...

The heliopause and the bowshock are the two remaining 'surfaces' for the Voyagers to cross, the regions defined by characteristics of the solar wind's interaction with the interstellar medium. The transmitters on the Voyagers are expected to still be operating when they cross the heliopause, estimated to be around 2015.
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Credits
Please give credit for this item to:
NASA/Goddard Space Flight Center Scientific Visualization Studio
Animators
- Greg Shirah (NASA/GSFC) [Lead]
- Ernie Wright (USRA)
- Horace Mitchell (NASA/GSFC)
- Tom Bridgman (GST)
- Trent L. Schindler (USRA)
Visualizer
- Cindy Starr (GST)
Writer
- Michael Starobin (KBRwyle)
Video editor
- Stuart A. Snodgrass (KBRwyle)
Scientists
- Jeffrey Hayes (NASA/HQ)
- Jennifer Rumburg (NASA/OSC)
Producer
- Rani Gran (NASA/GSFC)
Narrator
- Michael Starobin (KBRwyle)
Missions
This visualization is related to the following missions:Series
This visualization can be found in the following series:Datasets used in this visualization
SOHO
SOHO monitors the Sun with a variety of instruments. Among the SOHO instruments is the Michelson Doppler Interferometer (MDI) and the Extreme ultraviolet Imaging Telescope (EIT).
Dataset can be found at: http://sohowww.nascom.nasa.gov
See more visualizations using this data setAdvanced Composition Explorer (ACE)
Dataset can be found at: http://www.srl.caltech.edu/ACE/
See more visualizations using this data setC/NOFS (Collected with the Coupled Ion Neutral Dynamics Investigation (CINDI) sensor)
Dataset can be found at: http://cindispace.utdallas.edu/
See more visualizations using this data setAeronomy of Ice in the Mesosphere (AIM)
Dataset can be found at: http://aim.hamptonu.edu/
See more visualizations using this data setHinode (Solar-B) (Collected with the Solar Optical Telescope (SOT) sensor)
Dataset can be found at: http://solarb.msfc.nasa.gov/
See more visualizations using this data setTHEMIS
Dataset can be found at: http://themis.ssl.berkeley.edu/index.shtml
See more visualizations using this data setSTEREO
The STEREO mission consists of two Sun-observing spacecraft that will travel around the Sun on orbits slightly inside and slightly outside Earth's orbit.
Dataset can be found at: https://stereo.gsfc.nasa.gov
See more visualizations using this data setWind (Collected with the MFI sensor)
TRACE
The TRACE satellite views the Sun at ultraviolet wavelengths with high temporal (approximately 1-12 seconds) and spatial (1 arcsecond per pixel) resolution. Launched on April 2, 1998, it orbits the Earth in a Sun-synchronous orbit.
Dataset can be found at: http://sunland.gsfc.nasa.gov/smex/trace/
See more visualizations using this data setRHESSI (Collected with the X-ray Imaging Spectrometer sensor)
The RHESSI instrument is an imaging spectrometer observing the Sun at X-ray to gamma-rays (photon energies of 3 keV to 17 MeV) at time resolutions of a few seconds. (eV stands for "electron volt" and is a unit of energy. Note that photons of visible light have energies of 2-3 eV. 1 keV is a thousand electron volts and 1 MeV is a million electron volts.
Dataset can be found at: http://hesperia.gsfc.nasa.gov/hessi/
See more visualizations using this data setCluster
Dataset can be found at: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=8
See more visualizations using this data setCPC (Climate Prediction Center) Cloud Composite
Global cloud cover from multiple satellites
See more visualizations using this data setHipparcos Hipparcos Catalogue (Collected with the Telescope sensor)
Dataset can be found at: http://www.rssd.esa.int/index.php?project=HIPPARCOS
See more visualizations using this data setJPL/Horizon Orbital Ephemerides
Planetary ephemerides
Dataset can be found at: http://ssd.jpl.nasa.gov/?horizons
See more visualizations using this data setTOPEX Sea Surface Height Anomaly (Collected with the Poseidon sensor)
SSCweb ephemerides (A.K.A. SSCweb)
Satellite ephemerides
Dataset can be found at: http://sscweb.gsfc.nasa.gov
See more visualizations using this data setHipparcos Tycho Catalogue (A.K.A. Tycho 2 Catalogue) (Collected with the Telescope sensor)
Dataset can be found at: http://archive.eso.org/ASTROM/
See more visualizations using this data setNote: While we identify the data sets used in these visualizations, we do not store any further details nor the data sets themselves on our site.