Howdy Star Gazers and welcome to this episode
of Star Trails. Drew here, and I'll be your guide
to the night sky for the week starting May 25th
through the 31st. This week a new moon promises
darker skies, and have you ever wondered why
we have red, blue, and yellow stars, but no green
ones? More on that in a moment. Also, this is
going to be a shorter episode this week because
I'm losing my voice. I apologize for the raspy
narration. Whether you're tuning in from the
backyard, the balcony, or just your imagination,
I'm glad you're here. So find a cozy spot, let
your eyes adjust, and let's see what the sky
holds for us this week. We kick things off this
week with the moon in a waning crescent phase.
It's just a sliver in the pre -dawn sky, only
about 4 % illuminated. It's a great time for
stargazers to enjoy truly dark skies before moonlight
returns. Then on the night of May 26, we hit
the new moon. That means this is your prime window
for deep sky observing. No moonlight at all to
wash out faint galaxies or nebula. By May 31st,
the moon is back as a waning crescent, now about
24 % illuminated, and beginning to reappear in
the western sky after sunset. It's just enough
to show off that beautiful Earthshine glow that's
light reflected off Earth that dimly illuminates
the shadowed portion of the moon. Now onto the
planets, and if you've been listening in recent
weeks, this is going to all sound familiar, because
not much has changed. In the evening sky, you
can still catch Jupiter just after sunset in
the northwest. It's bright but slipping closer
to the horizon each night as it moves toward
conjunction with the sun. If you want to look,
get out early, around twilight, before it sets.
Mars is much easier to spot. You'll find it high
overhead after dark, shining with its trademark
reddish hue. It's not as bright as it was earlier
in the year, but still a rewarding target for
binoculars or a telescope. Meanwhile, in the
morning sky, Venus continues to dominate the
east just before dawn. It's the brightest object
in the sky aside from the moon, and it rises
well before the sun, perfect for early risers.
Just above Venus, you'll find Saturn in the southeastern
sky. It's much fainter than Venus, but still
visible to the naked eye under clear skies, and
a telescope will reveal those iconic rings. With
the new moon arriving on May 26, we have a perfect
window for deep sky viewing. So if you have a
telescope or even just a decent pair of binoculars,
here are five cosmic showpieces worth tracking
down. First up is Messier 13, the Great Hercules
Cluster. This dense ball of stars lies about
22 ,000 light -years away and is easy to find
in the constellation Hercules. Through a telescope,
it sparkles with thousands of tiny stars. like
someone spilled stardust across the void. Next
is Messier 5 in the constellation Serpens. It's
one of the oldest globular clusters we know,
about 13 billion years old. That means it's been
around since nearly the dawn of the galaxy. Look
for a tightly packed core surrounded by a soft
halo of light. Over in Virgo, check out the Sombrero
Galaxy or Messier 104. It's a spiral galaxy seen
almost edge -on with a bright central bulge and
a dark dust lane that gives it that classic hat
shape. It stands out even in modest scopes. Then
we have Messier 3, a globular cluster in Canes
Venetici. It's packed with variable stars, more
than 270 of them, which makes it a real laboratory
for studying how stars evolve. It's bright, round,
and rewarding through almost any telescope. And
finally, for a true showstopper, aim for the
Whirlpool Galaxy or Messier 51. It's a face -on
spiral interacting with a smaller companion galaxy,
and under dark skies, you might even glimpse
the spiral arms twisting outward. It's a favorite
for a reason. I'm sure you've noticed that some
stars are different colors. A star's color depends
on its temperature. But here's the twist. For
all the colors we can see in stars, there's one
that's curiously missing – green. You have red
stars, orange stars, white, blue, but green is
nowhere to be found, and that's strange because
the universe is packed with glowing, energetic
objects, and plenty of them emit green light.
So why doesn't the sky have any green stars?
Stars shine because of their surface temperature.
The hotter the star, the bluer its light appears.
The cooler it is, the redder. Our own sun, for
example, is classified as a G -type star with
a surface temperature of about 5 ,800 Kelvin.
It actually emits most of its light in the green
part of the spectrum, but we don't see it as
green. Stars don't shine in just one color. They
emit light across a wide range of wavelengths,
and our eyes, clever as they are, don't pick
out individual bands. When a star's spectrum
peeks in the green zone, our brain blends all
the surrounding colors together and interprets
the result as white. It's exactly the same principle
used in old -school televisions and computer
monitors. Those screens create white by blending
three colors, red, green, and blue, at the right
intensity. When all three are mixed evenly, your
eye sees white. So when a star peaks in green,
but also gives off a balanced amount of every
other color, your brain says, that's white, even
if green is doing most of the heavy lifting.
If a star somehow emitted only green light, just
that wavelength, no extras. We would see it as
green, but that's not how stars work. Their energy
is spread out in a smooth curve, not a laser
-sharp spike. Red and blue stars have lopsided
spectrums. They emit strongly in just one part
of the spectrum, so that color stands out. While
there may be no green stars, the universe is
still full of color. Take Beetlejuice, the reddish
shoulder of Orion. That color comes from its
relatively cool temperature, about 3 ,500 Kelvin.
Then there's Rigel at Orion's knee, blazing blue
-white with a temperature more than 11 ,000 Kelvin.
Sometimes atmospheric conditions even create
fake color effects. Stars near the horizon, for
example, can appear to shimmer red, blue, or
even green as their light passes through layers
of Earth's atmosphere. It's like the twinkling
version of a prism. And then there are optical
illusions. Take Alberio, a famous double star
in Cygnus. One component appears gold, the other
blue. That contrast can be so striking that some
observers describe the blue star as looking slightly
green. It's not actually green, but your eyes
get a little tricked by the color pairing. And
let's not forget, stars emit light beyond what
our eyes can see. Some glow fiercely in ultraviolet
or infrared wavelengths. That's where telescopes
like the James Webb and Hubble come in. They
can detect these invisible colors and convert
them into images we can see, giving us a richer,
more complete view of the universe. If the stars
spoke to you this week or if a question's been
on your mind, I'd love to hear it. Visit our
website StarTrails .Show where you can contact
me and explore past episodes. Be sure to follow
us on Mastodon, Blue Sky, and YouTube. Links
are in the show notes. Until we meet again beneath
the stars, clear skies everyone.