Astronomy with SalsaJ
Scaling the planets
In this activity, images of volcanoes and craters in the Solar system will be examinated using the software SalsaJ. Measurements of the size of craters and ejecta will be possible.
Volcanos and craters in the Solar System
This activity was initially prepared by Marie-Christine Angonin, Jérémie Lasue and Anne-Laure Melchior for students following modules of methodology in bioastronomy, proposed in the 1st year of Licence at the University Pierre and Marie Curie. It is also suited for pupils of secondary schools, but requires to spend a longer period. It has been tested in a scientific workshop (level 5th and 4th -- 12-13 years old) at the middle school named "Vieux Colombier" at Le Mans.
It uses the SalsaJ software.
Practical works of astronomical imaging.
images needed :
IO plume 1.jpg
Open the g2io_i24...small..jpg image
1: Observe the trajectory of the spacecraft, which is observing Io, the Jupiter satellite.
2: Explain the nickname of "pizza-pie of space"
Open the image
io_prometheus.fts (File/Open Image). (Credit: NASA.). It is about the
observation of an eruption of the Prometheus crater on Io (the nearest galilean
satellite of Jupiter) by the probe Galileo on June 28, 1997. The same area
observed by the Voyager's probe in 1979 presented already signs of volcanic
activity, it is possible that this volcano has been in eruption for more than
1: Describe this image.
2: Knowing that Io diameter is 3.630 km, determine the height and the extension of the plume of the observed eruption.
Open image: IO plume1.jpg (credit ESA/NASA). This image
(false colors) was taken by the probe "Galileo" on July 3, 1999, at an altitude
of approximately 130 km. The resolution is 1,3 km per pixel. One can observe a
gas plume and particles ejected under the effect of the volcanicity of the Io
3: Describe this image. Compare with the preceding one.
4: Determine the height and the extension of the plume of this eruption.
1: Observe the two images; describe the ground. Explain how the active lava flows evolved/moved between the two dates.
2: Evaluate the resolution of the image of right-hand side. Deduce of it the distance between the two active lava flows.
Open the image olymons face.fts (Credit: ESA/NASA.). It is about Olympus Mons, largest of the Martian volcanos and also largest known in the Solar system; it is located close to the equator of Mars.Its height is 26.000 m.
1: Describe the image.
2: By observing the indications of size of image (in top on the left), evaluate the resolution of this digital photograph. Then estimate the diameter of the volcano and the size of its caldera (crater).
3: Use the image olymonsprofile.fts to measure the height of caldera. Discuss.
4: Compare with Mauna leasing with Hawaii (alt. 4170 m) which is the largest terrestrial volcano, whose last eruption goes back to 1984. Its measurement is 3km x 5 km for a caldera depth, approximately 180 m.
Open the image encelade (Credit: ESA/NASA.). It is about an image of the Saturn satellite called Encelade. Approximately two weeks ago, Simon heard following information, of American origin: "a volcanic phenomenon was highlighted on the satellite Encelade de Saturne"; the Cassini probe sent images of what could be geysers... until now the scientists had thought that only the Earth and Io were the seat of active volcanic phenomena...
1: Describe the surface of this satellite
2: Measure its diameter after having evaluated the resolution of the image
Open the image enceladusfountains.jpg (Credit ESA/NASA). It is about a "crescent of the moon", photographed by the Cassini probe
1: Describe what you see
2: Measure the size of the plumes. Compare with the size of Encelade