GIS, Satellites, and Space: an Overview of Free Resources for Understanding Orbits and Distances

We are all enthusiast about the recent success of the Rosetta mission by ESA, which has reached the Comet 67P/Churyumov-Gerasimenko after a journey of ten years, travelling a distance of more than five times Earth’s distance from the Sun. This is the result of a huge work of astronomy, physics and engineering involving the trajectory of the Rosetta spacecraft and the orbit of the Comet 67P/Churyumov-Gerasimenko.

In my previous posts I have illustrated several applications about environmental monitoring though remote sensing, especially with satellite images. Thinking about satellites we can only imagine how far they are from the Earth surface. However, I have always been fascinated by their altitude, their orbit in the space, considering that the Earth itself is a satellite.
In this post I would like to share some interesting resources for understanding the size of our Solar System, in terms of orbit and distance from the Earth.

This blog is named From GIS to Remote Sensing, in fact between GIS (i.e. the information about the Earth) and Remote Sensing (i.e. the technology and science that allows for acquiring information remotely) there is really a long way. For instance several satellites such as Landsat are orbiting at about 705km altitude. Other satellites for the observations of meteorological phenomena have a geosynchronous orbit at about 36,000km altitude.
Satellite altitude is small if compared with Earth-Moon distance (i.e. about 363,100km). And Earth-Moon distance is very small if compared to Earth-Sun distance (i.e. about 150,000,000km). However, it is difficult to imagine such long distances.
An interesting perspective about these distances and orbits is provided in the following web applications and programs.

This is an online satellites viewer developed by NASA using the very interesting JavaScript library Cesium. This 3D GIS allows for viewing of the position of NASA satellites in real time.
The user can pan and zoom interactively, and select a specific satellite, showing information about position, altitude and velocity thereof. For instance, at this link you can see where is Landsat 8 right now, and the area of Earth surface that it is acquiring.

NASA Eyes on the Solar System

Developed by NASA, this program allows you to travel in time and explore the Solar System and NASA satellites in 3D; for the Earth, recent data for air temperature, carbon dioxide, carbon monoxide, sea level, ozone, ice and water are available.
Several tools are available for controlling the view, date, and time speed; it is also possible to share the view with an URL.
Unfortunately, this program is only available for Windows and Mac OS (for Linux users look at the next program).

The following video illustrates the main features of NASA Eyes on the Solar System.


The free and open source program Celestia is a wonderful representation of the Universe in 3D. With this program the user can virtually explore any planet of our Solar System and beyond the galaxy. All the planets are photo-realistic and their orbits are accurate, allowing us to "travel" in time and space. Moreover, additional textures, models and objects are available at this website, which make this journey even more realistic. For instance, you can actually see the distance between the Sun and the Rosetta spacecraft.
The program is available for all the Operating Systems.

The following is an image of the Rosetta spacecraft and the Comet  67P/Churyumov-Gerasimenko created using Celestia (the comet model can be downloaded from here).

Probably, the use of Celestia can rise several fascinating questions about the Universe and the size thereof.
Finally, I would like to mention the interesting site World Science U which offers free online courses about physics and the Universe. Multiple level course are available, allowing for a wide comprehensions of space and time, relativity, and the big bang theory. Following a brief video by the physicist Brian Greene about the evidence of the big bang.

Please, remember that a Facebook group and a Google+ Community are available for sharing information and asking for help about the Semi-Automatic Classification Plugin.
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