Goldfish Learn To Drive

Carbon curiosity
Massive stars with an orbiting partner 
star shed on average about twice as much 
carbon as loner stars do, 
Ken Croswell
reported in “How stars turn into carbon 
factories,” (
SN: 12/18/21 & 1/1/22, p. 12
).
When a massive star with a partner 
explodes, its carbon is cast into space, 
Croswell
reported. On the other 
hand, a single star’s core would have 
destroyed much of its carbon before 
such an explosion. Reader 
Bill 
Camenga 
wanted to know what 
becomes of the carbon in single stars.
“The carbon doesn’t just vanish,” 
Croswell
says. During a single star’s 
life, most of its carbon gets trans-
formed into oxygen. When the star 
explodes, that oxygen is cast into space, 
helping make oxygen the third most 
abundant element in the universe 
after hydrogen and helium. The exact 
nuclear reaction, he says, is carbon-12 + 
helium-4
→
oxygen-16 + energy. 
X-ray! X-ray! Read all about it!
In 1971, the first X-ray CT scan of a 
patient provided an unprecedented image 
of the human brain. Fifty years later, 
CT scans are still saving lives and helping 
researchers better understand the world 
around us, 
Conover'>Emily Conover
 reported in 
“Celebrating 50 years of CT scans” 
(
SN: 12/18/21 & 1/1/22, p. 44
). 
Several readers wondered whether 
radiation from CT scans should be a 
concern for those receiving them. 
Scientists have continually 
improved CT technology over the 
years, not only making it faster and 
higher resolution, but also decreasing 
the amount of radiation that people 
receive,
 Conover 
says. Although CT 
scans typically expose patients to 
more radiation than standard X-ray 
imaging, the amount of radiation 
from one scan is still relatively small. 
Depending on the type of CT scan, the 
radiation received may be less than 
the average background radiation a 
person gets from various sources in 
the environment over a year, she says. 
There is still debate among sci-
entists about the potential health 
effects of such low doses of radiation, 
Conover
says. When a doctor orders a 
CT scan, they typically will have deter-
mined that the benefit to the patient 
outweighs the small risk.
Correction
In “Pointed takedown of the mam-
moth hunters” (SN: 1/15/22, p. 22), 
archaeologist Vance Holliday of the 
University of Arizona in Tucson, not
Vance Haynes , weighed in on archae-
ologist Metin Eren’s hypothesis that 
ancient Clovis points were not used 
for hunting the tusked beasts.