9 November 2019 | New Scientist | 51Next in the series:
1 Mercury transits the sun
2 How to watch the Leonid
meteor shower
See Earth plough through
cometary debris
3 Venus and Jupiter in
conjunction
4 Mercury at its greatest
elongation
5 How to see the
Northern Lights
6 Find the Andromeda
galaxy
7 How to see Santa (the
ISS) on Christmas Eve
JUST last week we learned how
to identify the constellation of
Taurus, which starts to pop up in
November and can be viewed in
the night sky from pretty much
anywhere until around March.
This week, we are learning about
something much more fleeting:
the transit of Mercury across the
face of the sun.
On 11 November, Mercury, the
rocky, crater-covered world that is
the closest planet to the sun, will
pass in front of our star as viewed
from Earth. This will be visible
from much of Europe, Africa, New
Zealand, west Asia and America.
You might think all the planets
orbit the sun in the same plane,
but that isn’t the case. Mercury’s
orbit, which takes 88 Earth days,
is about 7 degrees off from ours,
which is why transits like this are
relatively rare: they only occur
about 13 times a century.
In total, the transit will take
about 6.5 hours. It will start at
12:34 GMT. Of course, the time
of day and weather in your area
will determine whether the sun is
even visible. If it isn’t, there will be
plenty of opportunities to watch
the event live on webcams or see
professional images of it. For the
most recent transit, in 2016, NASA
created an iconic composite photo
showing Mercury’s movement
as a dotted line across the sun’s
surface (pictured). It also recorded
a high-definition video.
It should go without saying, but
never look directly at the sun. This
is particularly true if you are using
a telescope or binoculars because
even a glimpse of the sun throughthese can blind you. Using a
telescope equipped with a special
filter is a great way to see a transit
like this, but most people don’t
have access to their own telescope.
In any case, there is a safe way to
watch the transit using binoculars,
if you have bright sunshine on the
day. Mercury is 4900 kilometres
across – tiny compared with the
sun – so you will need to mount
your binoculars on a tripod to
keep them still enough to make
out the diminutive planet.
A simple set-up will enable you
to view the motion of Mercury
without damaging your eyes. Take
a piece of cardboard and cut two
holes in it just big enough to fitover the binocular eyepieces. Hold
the cardboard over the binoculars
and point them towards the sun.
Then, stick white paper onto
another piece of card and hold this
up behind your binoculars so the
light from the eyepieces is shining
onto the paper. It is that simple.
The cardboard with holes for the
eyepieces stops light that isn’t
from the binoculars from hitting
the paper and drowning out the
image of the transit. You can cover
one of the lenses if you only want
to see one image, otherwise you
will have two that are identical.
Next week, you may need to
grab your coat – we will be outside
watching a meteor shower. ❚The closest planet to the sun is about to make a spectacular pass in
front of our star. Abigail Beall explains how to view it safelyPuzzles
Cryptic crossword, a
wood cutting riddle,
and the quiz p52Feedback
How to read 20,000
words a minute: the
week in weird p53Almost the last word
Why science
holds some of
us spellbound p54The Q&A
Neuroscientist
Henning Beck on
breaking rules p56Twisteddoodles
for New Scientist
A cartoonist’s take
on the world p53The back pages
NASA'S GODDARD SPACE FLIGHT CENTER/SDO/GENNAWhat you need
Binoculars
Tripod
Cardboard
Paper
For next week
Warm clothes
Abigail Beall is a science writer
in Leeds, UK. This series is
based on her book The Art of
Urban Astronomy @abbybeall
Stargazing at home 2 Week 1
Watch the transit of Mercury
Stargazing at home online
Projects will be posted online each week at
newscientist.com/maker Email: [email protected]