21/28 December 2019 | New Scientist | 89The back pages
ISSPHOTOGRAPHEDBYEXPEDITION56CREWM
EMBERSStargazing at home online
All the projects are posted at
newscientist.com/maker Email: [email protected]Abigail Beall is a science writer
in Leeds, UK. This series is
based on her book The Art of
Urban Astronomy @abbybeall
What you need
A clear night
One or more children (optional)
Starting on 4 January:
Science of cooking
Even if you are a great cook
already, you can make food
even more delicious if you
understand the science
behind it. Join Sam Wong,
a New Scientist reporter
and self-confessed food
nerd, to learn about the
ancient biotechnology
of cheese-making, plus
delve into fermentation,
curing, the science of the
perfect roast potato and
much more.
What you need
for week 1
Onions
A frying pan
Bicarbonate of soda
THIS is the last part of the
Stargazing at home series. We
started at the September equinox
and this week it is the December
solstice, when the northern
hemisphere is tilted at its furthest
from the sun and the southern
hemisphere is at its nearest.
It is also Christmas, and a great
time to spot the International
Space Station. If you have young
children, and the ISS is visible
from where you are on Christmas
Eve, it can be fun to tell the kids
it is Santa on his trip to deliver
presents around the planet.
The space station travels
at 28,000 kilometres an hour,
circling Earth every 90 minutes
or so, always from west to east.
That means the six astronauts
currently on board typically see
16 sunrises and sunsets each day.
For the rest of us, it means we
can observe the satellite moving
steadily across the sky, much faster
than planets and stars, but more
slowly than an aircraft.
If you live below 51.6 degrees
of latitude, you can see the station
passing directly overhead, as this
is the angle of its inclination.
If you live north or south of this,
such as in northern Europe and
much of Canada, it will always
be lower in the sky.
Because of Earth’s rotation, each
ISS orbit is 22.5 degrees to the east
of the previous one. That takes
it over most countries at some
point, although your chances
of seeing it will vary from once a
month to a few times in one week.
There have been astronauts
living on the ISS since 2000 as partThe International Space Station can look a lot like a sleigh flying
around the world to deliver presents, says Abigail BeallStargazing at home 2 Week 7
See Santa’s sleigh
Twisteddoodles
for New Scientist
A cartoonist’s take
on the world p95Feedback
The winners of our
inaugural awards
for absurdity p95Quiz of the year
Test your knowledge
of the science stories
from 2019 p92Puzzles
A bumper celestial
crossword and five
festive teasers p90The Q&A
Janelle Shane on
the delights of AI
strangeness p96of its mission to investigate life
in microgravity after the moon
missions came to an end. It is
108 metres, end to end, and
orbits 400 kilometres above
Earth’s surface on average.
To spot the station, it has to be
dark. The ISS can sometimes be as
bright as Jupiter or Venus, but this
depends on its altitude and the
amount of sunlight reflecting off
it. Satellites tend only to be visible
just after sunset or just before
sunrise. This is because they have
no light source of their own, so it
is only through the sunlight they
reflect that we can see them.
Unlike meteors, most satellites
don’t change in brightness as theymove across the sky. Some
satellites appear to gradually
brighten or even flash – these
are ones that are spinning. But
this will be a series of flashes,
unlike a meteor, which only
lights up once.
To check whether the space
station will be visible from your
location around Christmas, go
to spotthestation.nasa.gov. Tap
in your location and it will tell
you all the sighting opportunities
in the next two weeks. You can also
sign up for alerts telling you when
the station will appear.
Thanks for following the series,
and even if you don’t see Santa, I
hope your presents arrive safely. ❚