A red blob in sky
A RED BLOB IN THE NIGHT SKY: This is starting to happen a lot in the state of Texas. On April 10th, around 2:14 in the morning, amateur astronomer Abdur Anwar looked up from Big Bend National Park and saw a glowing red blob glide across the starry sky. "I photographed it using my Google Pixel 6a phone in night mode," he says.
"Is this a new aurora phenomenon?" he asks.
No, it's SpaceX.
About 90 minutes before the red blob appeared, a Falcon 9 rocket lifted off from the Cape Canaveral Space Force Station in Florida, carrying 23 Starlink satellites to low-Earth orbit (Starlink Group 6-48). After the satellites were deployed, the rocket's second stage executed a de-orbit burn, creating the nearly-spherical red light.
It's not the first time sky watchers have noticed this phenomenon. "We are seeing 2 to 5 of them each month," reports Stephen Hummel of the McDonald Observatory in Texas, who photographed a spectacular example last November.
The red glow is created by a chemical reaction. De-orbiting Falcon 9 rocket engines spray water (H2O) and carbon dioxide (CO2) into the upper atmosphere--as much as 400 lbs of exhaust gasses. A complicated series of charge exchange reactions between these molecules and O+ atoms produces red light at a wavelength of 6300 Ã…–coincidentally, the same color as red auroras.
Above: The launch of Starlink 6-48 ninety minutes before the red blob appeared over Texas.
Texas seems to be a great place to observe the phenomenon. The state is favored because, for Starlink missions launched from Florida, it's where a de-orbit burn will splash the rocket's second stage safely into the South Atlantic. The burns happen about 90 minutes after launch--just when Anwar saw the blob.
Would you like to see one? Check the SpaceX schedule for night launches, and look at the sky 90 minutes after liftoff. Human eyes are not very sensitive to the 6300 Ã… wavelength of the red glow, but cameras have no such trouble. Take a short nighttime exposure and submit your images here.
Comments
Post a Comment