“It’s a bird. It’s a plane. No, it’s a Starlink satellite.” That was the refrain ringing around social media as sky watchers gazed in amazement at the string of glowing lights racing across the early morning horizon. The view, a string of string lights cruising along in precision formation, is the calling card of SpaceX’s Starlink satellite train one that has become familiar to amateur astronomers and recreational stargazers the world over.
For those who were privileged enough to witness the show on July 26, the mission was just another step on SpaceX’s ambitious rung to filling low Earth orbit. Right on schedule at 5:01 a.m. Eastern Time, a Falcon 9 rocket departed from Cape Canaveral’s SLC-40, sending 28 new Starlink satellites into the expanding constellation. What made this flight stand out was less the payload, but rather the hardware that carried it: the first stage Falcon 9, which was making its 22nd flight, a testament to the engineering prowess and the rocket reusability science maturing at SpaceX.
Booster reuse is no happenstance. SpaceX refurbishment plan leverages material science and additive manufacturing technology, with the engineers creating hardenable ceramic coating and reentry-resistant alloys that can endure launch and reentry stresses. Propulsion devices have to be designed differently for reusable rockets, says MIT’s Zack Cordero. “With liquid-fueled rocket engines that are reusable, you need to be safe for many cycles and lose some performance so you feel less stress.” The Merlin engines of the Falcon 9, and newer Raptor engines under development, are leading this transition, maintaining turnaround quick and reducing launch cost by a factor of perhaps ten.
But for most, the spectacle really starts when the engine roar recedes. After the satellites have achieved orbit, they create a glistening “train” that can be seen with the naked eye a brief but beautiful sight. The phenomenon is most striking on the days immediately after launch, when the satellites are still congregated in a low parking orbit before they spread out to their operational altitudes of approximately 342 miles (550 kilometers). Their reflective coatings reflect the Sun’s light, casting a string of pearls that shine brighter than many stars, and sometimes even equal Venus in brilliance.
It has become a hobby to track these trains through a collection of apps and web services. The Satellite Tracker software, for instance, enables one to graph the precise time and place of approaching passes, and sites such as Heavens-Above and findstarlink.com provide real-time maps of the continually changing positions of the constellation. The ease of access to the instruments has made satellite observing level for everyone, turning amateur observers into citizen scientists who can help track this record-breaking orbital infrastructure.
Their release, however, of Starlink satellites 7,875 in orbit as of June 2025, with ambitions for up to 42,000 have raised pressing questions among astronomers and environmental researchers. The International Astronomical Union has cautioned, “Satellite constellations can pose a significant or debilitating threat to important existing and future astronomical infrastructures.” The satellites’ brightness, especially on their initial orbits, can create streaks through telescope images and render optical as well as radio observatory data unusable. The Vera Rubin Observatory, designed to map the universe in exquisite detail, is one of the most vulnerable.
SpaceX has countered with a succession of engineering fixes, from anti-reflective coatings and deployable visors that block out glare. The V2 satellites add these upgrades, but the issue remains: as the satellites get bigger and more complex, some scatter more blue light and are seen in new ways. “This is an effect, we believe, of the coating that has been applied to the new Starlink satellites, and generally speaking it is to make them less visible, and that is a good thing,” says planetary astronomer Aaron Boley. But the combined effect of thousands of satellites remains a daunting challenge for ground-based astronomy.
In addition to light pollution, the sheer number of objects in low Earth orbit has rendered Starlink the primary source of collision risk in space. Around 1,600 close encounters per week are generated by Starlink satellites, states Hugh Lewis, who leads the Astronautics Research Group at the University of Southampton, a number that increases with each launch. SpaceX satellites have autonomous collision avoidance systems, yet the Kessler effect, a chain of collisions born from debris, grows every day.
Environmental concerns are also under scrutiny. Starlink satellites, at the end of their five-year mission lifetimes, will deorbit and incinerate in the atmosphere. While it reduces long-term space debris, scientists such as Aaron Boley argue that the resulting aluminum oxide particles can change atmospheric chemistry and even the climate of the Earth. Alumina scatters light at certain wavelengths and if you inject a lot of alumina into the atmosphere, you are going to have scattering and eventually change the albedo of the planet, cautions Boley.
In spite of these issues, the Starlink project has seen practical uses, deploying high-speed internet to remote and disadvantaged communities, facilitating disaster response, and closing the digital divide. SpaceX insists it is absolutely committed to finding a way forward so our Starlink project doesn’t impede the value of the research you all are undertaking, as SpaceX vice president of satellite government affairs Patricia Cooper informed astronomers.
For now, the glorious trains that cover the dawn and dusk skies are a testament of human genius and an admonition about the fine trade-offs hanging on the edge of space technology. Each launch is not only an engineering accomplishment, but a challenge to contemplation on what is achieved, what is lost, and on what the night sky will be like for coming generations.
