A telescope is the astronomer’s basic tool. It makes
distant objects appear bigger and reveals their
detail. Telescopes work by using a lens or mirror
to collect light and bring it to a focus, producing
an image. Reflectors, which use a mirror, are the
most widely used type of telescope – the bigger
the mirror, the more powerful the telescope and
the better the view.Telescopes
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Magnifying eyepiece
is at 90º to the main
tube for ease of useRefracting telescope
uses a lens, contained
within the body of the
telescope, to collect
and focus lightTHROUGH BINOCULARS ▲
The Orion Nebula is a massive
star-forming cloud of gas and
dust. The nebula becomes more
obvious when looked at through
binoculars – two low-powered
telescopes working together.
In standard binoculars the
two main lenses are about
5 cm (2 in) wide and the image
is magnified seven times.IMPROVED VIEW ▶
A more powerful telescope
improves the view of the nebula.
Across the world there are about
50 telescopes with mirrors 2–5 m
(6.5–16.5 ft) across and another
20 with mirrors up to 10 m (33 ft)
across. These large telescopes are
located on mountain-top sites
where the air is clear and still.
Computerized controls adjust
their position, keeping them
tracked on their target as
Earth turns.NAKED-EYE VIEW ▲
The constellation of Orion is easily
visible to the naked eye. On a dark,
moonless night, a faint, fuzzy patch
of light may be visible below the
three stars of Orion’s belt. This is
the Orion Nebula.146_147_Telescopes.indd 146 17/01/19 11:49 AM