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Salutations celestial sight seers! I'm David Fuller, welcome to Eyes on the Sky; what's
up this week?
Cancer the Crab is a constellation of the zodiac, so the Sun, Moon and planets all pass
through its stars at some point throughout the months and years. However, that doesn't
mean it's a bright constellation - last week we learned that Earthlings are looking up
and out of the Milky Way in the coming months, so there aren't as many bright stars to see
at this time of year. However, with spring here, we'll eventually have swarms of bees,
and this week we'll look for the Beehive Cluster, that is located in Cancer.
Let's start by getting familiar with this part of the sky. The bright stars of winter
are off towards the southwest; Orion is sinking towards the horizon at 3 hours after sunset.
To his east is the brightest star after the Sun, Sirius. Above that is first magnitude
Procyon, and further up from it are the twins Pollux and Castor. Between those stars and
the orange-red star Betelgeuse in Orion is the brilliant Jupiter - you can't miss it,
Jove will be the brightest point of light in the sky here, outshining even Sirius. Now
draw a LONG imaginary line towards the east from Jupiter, along the line of the ecliptic,
which follows the zodiac constellations. Trace the ecliptic by holding up two outstretched
arms with your hands like this, measuring approximately 45 or 50 degrees to find the
star Regulus. You've found this first magnitude star when you see a sickle shape, or backwards
question mark. In the world's highly light polluted locations, the top of the sickle
may be invisible, and some of the third magnitude stars difficult to see. Use binoculars to
locate them. So if Gemini and Leo are both zodiac constellations, what did we skip on
our way there in that "blank" looking section of sky? Well, Cancer the Crab of course! Don't
buzz away just yet - the Beehive is next.
Dark Sky Fact: A sunset glow has red-shifted light. This helps your body recognize night
time coming. But computer screens have blue-shifted light, so download the free program f.lux
to automatically change your computer screen every day to red-shifted light when the light
outside does... at sunset.
Now let's use binoculars. The stars get faint here, but with binoculars even from light
polluted areas stars as faint as fifth, sixth and seventh magnitude are visible. Start at
Regulus, and follow the sickle shape up and around. Look at 3.4 magnitude Zeta Leonis.
This star is a neat sight - two 6th magnitude stars are on either side of it. Now turn to
the west (right) and go a full field of view to Epsilon Leonis. This line - Zeta to Epsilon
- is the general direction we want to go. With Epsilon centered, move ever so slightly
in that same direction. You'll see 4th magnitude Alterf at the edge of your field - in fact,
it may be there with Epsilon centered. Center it, and keep going. Before Alterf leaves the
field, you'll see 5.2 magnitude Xi Cancri enter the field. It will be a magnitude fainter
than Alterf. Sixth magnitude 79 Cancri is right next to it. Now continue until you see
two 4th magnitude stars. The northern one, Asellis Borealis, is 4.7 magnitude and fainter.
The southern one, Asellis Australis, is brighter, at magnitude 4.0, similar to what Alterf was.
But what lies between them is what's magnificent. You've just found where the Beehive is! Sometimes
it is also known as "The Praesepe," a Latin word for "Manger."
This cluster is HUGE - spanning 95 arc minutes of sky which is three Moon diameters across,
so it is too large to see except in very rich field telescopes with expansive apparent field
of view eyepieces. This mean binoculars really ARE best to use here. The Beehive contains
around 1000 stars, though you're likely to spot the brightest 6-th to 8-th magnitude
ones with binoculars from most areas. For more information, visit eyes on the sky dot
com.
Along The Ecliptic: Mars is starting to gain some separation from Spica, but remains within
5 degrees of the star. Nearing opposition, check out the Red Planet now while it is larger
than 14 arc seconds across.
That's all for this week. Keep your eyes on the sky and your outdoor lights aimed down,
so we can all see, what's up. I'm David Fuller, wishing you clear and dark skies.