Chapter 1 Understanding Satellite Imaging

Recently, I received an intriguing question from one of my subscribers:

“Hello. I've heard that satellites in orbit can read a newspaper laid out on the ground. Is this fact or fiction?”

To answer concisely, no, satellites in orbit cannot "read" a newspaper on the Earth's surface. Achieving this would require satellites equipped with extraordinarily large cameras, with lenses measuring several meters in diameter.

What sets the threshold for the smallest object that a satellite camera can identify? This depends on what is known as angular resolution, which is the smallest angle between two objects that the camera can differentiate. For instance, the Hubble Space Telescope boasts an angular resolution of 0.05 arc seconds, enabling it to detect objects on Earth as small as 5 centimeters across. However, such small features would only occupy a single pixel in a Hubble image.

Images demonstrate distinguishable objects measuring 5, 10, 20, and 40 centimeters.

Note that these are examples from aerial photography, not satellite imagery.

Civilian satellites typically have lower optical performance than the Hubble, with a minimum discernible object size of approximately 40 to 50 centimeters. When zooming in on a city in Google Maps, you see cars, people, and trees—these images are derived from aerial photography. Google Maps does not utilize satellite images with a resolution finer than 40 centimeters per pixel.

Military reconnaissance satellites' capabilities remain largely unknown due to the confidentiality surrounding their technology. However, it is unlikely they possess optics that significantly outclass the Hubble's resolution. For example, the Keyhole-11 satellite, one of the most renowned U.S. spy satellites, was manufactured on the same assembly line as the Hubble and has a similar exterior appearance.

To clearly read letters from a newspaper on the Earth’s surface, a satellite would require a camera lens tens of meters in size. Currently, we lack the technology to produce satellites with such extensive optics. For instance, the James Webb Space Telescope features a mirror diameter of just over 6.5 meters.

While military advancements often surpass civilian technologies, it remains unfeasible for any nation's military to have a spy satellite equipped with a lens of such massive proportions. Such a large satellite would be easily observable by amateur astronomers in low Earth orbit, which is not currently the case.

Read more: Can the US flag on the Moon be spotted with a telescope?

The first video discusses the unsettling implications of what satellites can observe from space, shedding light on privacy concerns and technological capabilities.

The second video explores the visual landscape of satellites in the sky, offering a 360-degree/VR perspective on satellite visibility and their impacts on our view of the cosmos.

If you wish to see more space-related articles, feel free to clap! Subscribe to my channel and submit your questions, which I will address in upcoming posts. If you appreciate my work, consider supporting me through this membership link for just $5 a month, which will help us enhance our content even further.