# Level 0

That is true. This [site](https://stuffin.space/) shows, how many are in there. Note, we are focused on satellites, facing Earth's surface, and monitoring various parameters of Earth's ecosystems. [Here](https://pudding.cool/2017/10/satellites) is a brief history of this kind of satellite. And another way around: [here](https://earthengine.google.com/timelapse/) you can check landscape changes over time, captured by Landsat (starting in 1984! - actually, the first Landsat satellite was put into orbit in 1972, but this app contains data starting 1984) all over the globe, [including Antarctica](https://earthengine.google.com/timelapse/#v=-67.2487,-66.06831,3.77,latLng\&t=2.96\&ps=50\&bt=19840101\&et=20201231\&startDwell=0\&endDwell=0,).

Now it is time for more in-depth reading. Be prepared for new [terminology](https://appliedsciences.nasa.gov/sites/default/files/2022-03/RS_Terminology.pdf)!

This [article](https://www.earthdata.nasa.gov/learn/backgrounders/remote-sensing) will give you a general understanding of technology, satellite types, and satellite imagery properties.

Alternatively, there is a selection of free self-paced mode courses to take:

* [Sections 1A and 1B of Fundamentals of RS](https://appliedsciences.nasa.gov/join-mission/training/english/arset-fundamentals-remote-sensing) by NASA ARSET
* [Land in Focus](https://eo-college.org/courses/landinfocus/) - Basics of Remote Sensing by ESA
* [Fundamentals of RS](https://eolearning.planetek.it/course/view.php?id=12) by Planetek