Intern Gali Polichuk discovers her inner geospatial expert by using SkyTruth’s intuitive, interactive maps

As a sustainability major, I anticipated that my interest in conservation would come in handy during my SkyTruth internship. But monitoring the planet with satellite imagery? What an unexpected surprise.

My main role as a communication intern includes writing blogs, creating social media content, and editing newsletters, among other activities. From my intern duties, I quickly became aware of the role satellite imagery has played throughout SkyTruth’s history. My first meeting with Brendan Jarrell, SkyTruth’s Geospatial Analyst and Internship Program Coordinator, left me feeling underwater because I had never been exposed to the complex world of geospatial data and satellite monitoring before. Although I finished that meeting with more questions than I thought I could ever have, I was also extremely excited to know SkyTruth gives us the power to monitor our entire planet.

SkyTruth’s monitoring application, developed in Google Earth Engine, shows images from the European Space Agency’s (ESA) Sentinel-1 and Sentinel-2 satellites. These satellites are extremely useful, but understanding the difference between them is essential for monitoring. As the ESA notes, Sentinel-1 radar imagery is helpful to monitor oil slicks in the ocean, discover land changes, and map sea ice. On the other hand, Sentinel-2 multispectral imagery is useful for monitoring land use, such as vegetation, soil, and coasts.

Sentinel-1 satellite image from January 29, 2023, showing a likely oil slick in the Gulf of Guinea. The sensitivity of Sentinel-1 radar images to the roughness of the ocean’s surface makes them an effective tool for detecting slicks.

As a geospatial newbie, I could not help wondering what made these satellite images so telling. One way to understand this is to consider the detection of oil slicks at sea, a key role of our newly launched Cerulean platform.

Sentinel-1 imagery is usually presented in grayscale (i.e. black and white) and its radar penetrates any clouds, which makes it great for tracking oil spills in the ocean. In contrast, Sentinel-2 imagery relies on reflected sunlight, so it is affected by clouds and various atmospheric effects, as well as sun glint (bright patches reflected off water)—this makes tracking oil spills and other features in the ocean challenging.

As I dove deeper into skytruthing, I discovered lots of other cool tools to monitor our planet, such as Landsat 8 and Landsat 9 imagery. The National Aeronautics and Space Administration (NASA) and the United States Geological Survey (USGS) jointly launched Landsat 8 and 9 in 2013 and 2021, respectively, with the objective of “monitoring, understanding, and managing the land resources needed to sustain human life.” These multispectral images are collected frequently, so you can find the latest information from these satellites.

Learning how to monitor using satellite images is a process of trial and error. It requires a lot of patience and persistence. For that reason, having the help of the SkyTruth team was valuable to understand and identify diverse elements in the environment, such as oil slicks, natural features, and other characteristics visible with satellites. After a few tries, I understood how it worked and began feeling comfortable with the tools.

One morning I was monitoring the region I was assigned to with Sentinel-1 imagery. Suddenly, I saw two irregular dark shapes in the ocean in the Gulf of Guinea. I was not sure whether the discrepancy I found was an oil spill, so I sent the images to the geospatial experts on the team. Everyone was tremendously supportive and eager to find out more about this discovery. After receiving help from Brendan, Geospatial Engineer Christian Thomas, and even our CEO, John Amos, I learned that these irregularities were the typical sign of an oil slick. The first slick coincided with oil platforms in the area. The second slick did not correspond to oil infrastructure, but may have been oily wastewater discharged from a passing ship.

Finding my first oil slicks was as satisfying as learning how to ride a bike or doing my favorite hobbies, like completing a successful embroidery project. At that moment, I understood that satellite monitoring is fun, empowering, and—importantly—possible for anyone!

The day after that first discovery, I was even more eager to monitor with SkyTruth’s tools. In fact, it has become a regular part of my job as a communications intern—even though I’m surprised to say this, I enjoy doing it.

Satellite monitoring is important for several reasons, such as urban planning, natural disaster response, and public safety. For me, the most powerful aspect is being able to track environmental changes because of anthropogenic forces, meaning impacts and activities caused by humans. We need to hold institutions accountable for their actions by discovering oil slicks, deforestation patterns, and other activities harmful to the environment wherever and whenever they happen.

The first steps toward change are transparency, accountability, and visibility of these problems. Being able to compare the Amazon forest between the present and 20 years ago to notice the effects deforestation, increased greenhouse gas emissions, and urbanization have in natural areas is crucial to promote positive change toward a better, healthier future.

Want to get started tracking movements on the planet? Head to our SkyTruth Alerts platform, which is frequently updated to include the latest satellite imagery and data allowing anyone to detect the most recent changes to ecosystems worldwide. I think you will find—just like I did!—that it’s easy to use. But if you get stuck, we provide this guide to give you a hand. If you still need help, you can always reach out to the SkyTruth team for assistance.

Students, teachers, retirees, advocates, researchers, and anyone else passionate about protecting the environment can use SkyTruth Alerts for free. Create an account today, and discover its fantastic features!