16 November 2019 | New Scientist | 51Next in the series:
1 Mercury transits the sun
2 How to watch the Leonid
meteor shower
3 Venus and Jupiter
in conjunction
Two planets in the
same part of the sky
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
ON ANY clear night, you can
expect to see between five and
10 meteors in an hour. But in a
meteor shower, they are far more
frequent. To understand why, we
need to know what causes them.
Meteors are streaks of light in
the sky created by bits of rock and
metal entering Earth’s atmosphere
at high speed. They are usually
no bigger than a grain of rice,
though some are much larger.
As they smash into air particles,
the friction of these collisions
creates heat and makes the
objects burn brightly.
Earth regularly encounters
particles like this as it orbits the
sun. A meteor shower happens
when it passes through the trails
of dust and rock left by asteroids
and comets. In the case of the
Leonid shower, Earth is ploughing
through debris from comet 55P/
Tempel-Tuttle, a 3.6-kilometre-
wide comet with a 33-year orbit
around the sun.
Bits of space debris are called
meteoroids. Any that are large
enough to survive entry into
Earth’s atmosphere and reach
the ground are called meteorites.
Earth moves through the trails
of certain comets at specific times
of year, so spotting meteors can
be easy if you know when to look.
The Leonids can be seen between
6 and 30 November this year,
peaking on 17 November.
Meteor showers tend to be
named after the constellation
in which they appear to start in
the sky, a spot called the radiant.
For the Leonids, the radiant is the
constellation of Leo, which canbe seen all over the world because
it is a zodiacal constellation, as we
learned in week 7 of the first series
of stargazing at home.
To see a meteor shower, it is best
to get as far from light pollution as
possible. To check whether an area
is dark enough, look for the Little
Bear constellation, also known as
Ursa Minor. If you can see it, you
will be able to see meteors.
To find Leo, first find the Plough,
also known as the Big Dipper, in
the constellation Ursa Major. In
week 2 of the first series, I showed
how to use the Plough’s pointer
stars to find Polaris. In this case,
use the same stars, but go in the
other direction to find Leo. If youlive somewhere that doesn’t have
a view of the Plough, use a star
chart or an app to find Leo.
Now it’s time to get comfortable.
Maybe bring some friends, a hot
water bottle or your drink of
choice. If it is your first time
watching a meteor shower, don’t
try to take photographs. You will
struggle to capture the brief
flashes, and you won’t enjoy the
show. Leave that for next time.
If you don’t have good weather
on the night of 17 November, don’t
worry: the Leonids are visible until
the end of the month. Then in
December, we get the Geminids.
There will always be another
chance to see a meteor shower. ❚Earth’s orbit sometimes passes through comet trails, which we see
as meteor showers. Abigail Beall explains how to spot themPuzzles
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JERRYSCHAD/SCIENCE^ PHOTOLI
BRARYWhat you need
Warm clothes, possibly
For next week
A place where you can
see the western horizon
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 2
Watch a meteor shower
Stargazing at home online
Projects will be posted online each week at
newscientist.com/maker Email: [email protected]