WWW.ASTRONOMY.COM 47Supernova remnant
Veil Nebula ( 1 ,4 7 0 light-years)
The Veil Nebula has many names and
several NGC numbers because it takes
up nearly 3° of the sky. (By comparison,
a Full Moon takes up 0.5°.) It forms a
partial ring of ionized gas in Cygnus that
shows incredible detail with modest to
large apertures under dark skies. The
progenitor was a massive star that lit up
the night sky when it exploded some
3,000 to 8,000 years ago.
Observing tip: Under a dark sky, the Veil
Nebula may be glimpsed with high-quality
binoculars. It looks impressive through a
wide-field telescope with enough contrast
to bear magnification well.Globular cluster
M4 ( 7 ,000 light-years)
Scattered around the Milky Way like
mosquitos around a skygazer are spheri-
cal groups of stars called globular clusters.
Their origin is far different from open clus-
ters, forming at the same time as the galaxy.
Some are associated with the cores of dwarf
galaxies ripped apart as they collided with
the Milky Way. The distance between stars
in the cluster may average about 1 light-
year, but near the core, they may be only
billions of miles apart. (A light-year is about
5.9 trillion miles, or 9.5 trillion kilometers.)
M4, located close to Antares (Alpha
Scorpii), is a favorite of many amateur
astronomers for several reasons: It’s easy
to find, it’s bright, and its stars can be
resolved in telescopes with apertures as
small as 6 inches. This ball of stars is 75
light-years in diameter with an estimated
age of 12.2 billion years. You are looking at
stars nearly three times older than the Sun!Observing tip: This is one of the easiest
globular clusters in the sky to resolve. To
spot it, look for a bright bar of stars
bisecting the cluster.Large galaxy
Andromeda Galaxy
( 2. 5 million light-years)
The Milky Way is the second-largest
member of the Local Group, a cluster con-
sisting of nearly 60 galaxies. Only three
galaxies — the Andromeda Galaxy (M31),
the Pinwheel Galaxy (M33), and the MilkyWay — are large; the rest appear as mere
wisps by comparison.
The Andromeda Galaxy is the closest
large galaxy. Somewhat bigger than our
home galaxy, it spans 220,000 light-years
and contains an estimated 1 trillion stars.
(For comparison, our galaxy contains 200
to 400 billion stars.) M31 is inclined 18°
from edge-on, which intensifies its bright-
ness, just like the Helix Nebula is brightest
where we look through its edge. At magni-
tude 3.5, it can be seen with the naked eye
in suburban skies. Under dark skies,
Andromeda spans a whopping 3.1°, or
roughly the width of six Full Moons.Observing tip: M31’s dwarf elliptical
companions, M3 2 and NGC 2 05, are visible
in the same field of view through a small
telescope.If you like creating themed observing
lists, this is a place to start. Use the next
cloudy night as an opportunity to research
other targets. What is the closest red
giant? The nearest O-type star? Dark neb-
ula? Peculiar galaxy? Dwarf elliptical? Your
choices are vast because the universe has
incredible diversity with options for every
observer — from those using their naked
eyes to those viewing through behemoth
telescopes. Start with the objects in this
list, and then take it to the next level.Alan Goldstein has been observing deep-sky
objects for 40 years and writing about them
for nearly as long.Andromeda Galaxy (M31)Veil NebulaTONY HALLAS