Many artificial satellites move across the sky on a clear night. They look like slow-moving stars and somehow bright. Usually, they take an average of 10 minutes from horizon to the next. It is possible to spot satellites moving together in a group of three or two.
The International Space Station and the Hubble Space Telescope are famous satellite stations . You can read on to find out what you need to start observing satellites as they orbit the earth.
Observing Satellites
Satellites have no exterior lights. Though, having these would still not amount to much on the ground. Anytime you spot a satellite, it is the reflected sunlight that you see. Some have an array of solar panels that reflect plenty of sunlight, making it possible to spot them.
Imaging satellites from the ground can be quite difficult. These objects have strict schedules; they are far away, small, and move fast. You need to do a little preparation to beat these challenges.
Observation Scheduling
There are two types of satellites, Geostationary and polar-orbiting. Polar-orbiting satellites are known for flying at low altitudes. The circle covers the entire earth within 100 minutes. These types of satellites are always on the move, imaging the earth and measurements.
Unfortunately, the polar-orbiting satellites did not allow continuous observation. This promoted the invention of geostationary satellites to enable this. They have the same speed as the earth’s rotation. As they hover in one area, they allow continuous observation. They have limits in that they cannot observe the polar regions due to the earth’s curvature. You need to keep a few things in mind when scheduling an observation.
Orbital Mechanics
Due to orbital mechanics, Low Earth Orbit satellites have a precise time they pass an observation site. The rest of the time, the satellites are below the horizon, meaning they are not visible. Popular websites contain pass times. You can also get orbital elements from US Strategic Command and feed the data in some software such as Heavens at to get the pass times.
Factors such as satellite’s orbit inclination affect their pass time by making it more visible to people at a lower latitude. The orbit’s height also affects these times and the satellites’ role.
Illumination
You cannot schedule a viewing by having the pass time only. You need to factor in illumination. To observe the satellite perfectly, you need to be in the dark while the satellite needs to be in the light. For this reason, you need to be interested in the passes happening before the sunset or shortly before the sunrise. You can spot the ISS in the city lights. But, to spot other satellites, you need to be far away from these lights.
Clouds
One last thing to look at when scheduling an observation is the sky. You need to have clear skies to observe a passing satellite perfectly.
How to Handle Movement
Though you can spot a good satellite pass, you may have a hard time imaging because of the movement. If you want to photograph your sighting, you need first to verify the pass time using your naked eye or binoculars. The first pass and the ones that follow will last a few minutes. For you to capture the image with a camera, you need to deal with this movement. Here are a few ways to do so.
Fixed Pointing
Refers to, pointing your imaging equipment in a specific direction and capturing the photographs when the satellite is in sight. Use a high zoom level camera to take high-resolution pictures. You need to not only point the camera but also take the picture at the right moment.
Motorized Tracking
With this method, you fix the telescope or camera on a motorized mount. Using the orbital elements, a computer instructs the motors to track the satellite. For this, you need dedicated hardware with a wide field of view telescope. This helps to target and keep the telescope focused on the satellite. Unfortunately, this method is expensive.
Manual Tracking
Another option is to keep the telescope focused on the satellite, ensuring it stays in the field of view. You can get more pictures this way, hopefully with reduced motion blur. You avoid purchasing tracking hardware with this option.
It is still challenging to keep the object perfect still and in the field of view. Thus, you need to keep the exposure relatively short. You also reduce the vibrations impact of moving the telescope.
Geo Satellites
There are satellites that appear fixed in the sky. The geostationary orbit satellites allow you to take stunning videos and photos. Fixed pointing and long exposure duration can work best in this case.
Today’s Sky
Satellites have provided us with essential images. These images have increased our understanding of the earth’s systems and processes. Currently, satellites have proven to be our biggest source of data. They check, measure, and understand the earth’s climatic and aquatic environments. Satellites have led to revolutionary advancements in fields such as map creation.
There has been an increase in the number of satellites in the skies since the first launch. This increase has helped bring down data costs. Vast free online databases are offering all types of data. You can go through this information to find out more about the various satellites orbiting the earth.
Conclusion
One of the most prominent satellites to watch is the ISS. You can also watch Elon Musk’s SpaceX Starlink satellites contributing to the company’s 57 satellites. When scheduling a viewing, ensure:
- You have the correct pass times.
- It’s not enough having the correct pass times; they need to be the best times. Before the sunset or sunrise for the best illumination. During these times, you are in the dark, and the satellite is in the sunlight, making viewing possible.
- Remember, clouds can affect your viewing. You need a clear skyline for satellite observation.
- When imaging polar-orbiting satellites, you need to factor in how you will handle movement. You can use fixed pointing, manual tracking, or motorized tracking. Use the option that is within your budget.
Did you know that there are similarities when imaging satellites from the earth and a satellite? These tasks could be affected by orbit mechanics, cloud cover, and sunlight. The Propagation laws offer constraints in both cases. Taking satellite images is an exciting hobby that you can take up.