Salutations celestial sight seers!
I'm David Fuller, welcome to Eyes on the Sky; what's up this week?
Last week we looked at objects in Monoceros, the unicorn.
Let's finish up in and around there, since the Moon is out of the way this week.
Begin at Sirius, the brightest star in the night-time sky, which is easy to find nearly
due south at 8:00 or so, and sits 20 degrees down and left of Orion's belt stars.
Using binoculars, place Sirius to the bottom of the field; you should see these three 4-th
magnitude stars; these are Gamma, Iota and Theta Canis Majoris.
There is a slightly dimmer 5-th magnitude star between them.
Draw a line from from Sirius through Theta.
Those two stars are 5 degrees from each other, which will place them on opposite sides of
the binocular field.
Continuing in the direction of that line, move a similar distance, now placing Theta
where Sirius just was.
Where Theta had been, you may spy a faint haze in your binoculars, but you'll likely
need to use your finder on your telescope to locate this area.
Past Theta, you should see this small triangle of 6.5 magnitude stars.
That “haze” is the open cluster Messier 50; at 16 arc minutes of angular diameter,
it can handle medium magnification in many telescopes.
It is near a trapezoid shape of 7-th magnitude stars.
The cluster resides some 3000 light years from us, and is approximately 20 light years
across, containing around 200 or so stars, some as bright as 8-th and 9-th magnitude,
which means a telescope is likely needed to see it.
Darker skies and dark adaptation will help you see more.
But a neat color contrast in this cluster is this 7.8 magnitude red giant some 1000
light years further off than the cluster, which is composed of blue-white “B” class
stars along with some yellow giants, with an age of about 78 million years.
Dark Sky Fact: Even small amounts of light can disrupt your sleep.
According to Dr. Joseph Mercola, “Even the tiniest bit of light in the room can disrupt
your internal clock and your pineal gland's production of melatonin and serotonin.”
The use of sleep mask can help, but updating our outdated and wasteful lighting on our
homes and on our streets will go a long way towards helping all of us sleep better.
Again using binoculars, and starting at Sirius while this time moving towards Gamma, we'll
be moving through an area of the Milky Way, and some fifth-magnitude stars will be visible,
here in this area.
Continue through this shape til you reach another 5-th magnitude star, that is yet another
far-off red giant - 3400 light years away.
When you see this, just beyond it is Messier 47, a somewhat large and sparse open cluster,
but one with quite a few more brighter stars in it than Messier 50 had.
Though small, it is much more easily visible in binoculars, and a telescope at low power
will reveal more stars, so use your magnified finderscope to “hop” here.
With about a dozen suns at 8-th magnitude or brighter in a span the size of the full
Moon, and keeping in mind this cluster is only 1600 light years away, this cluster will
look a bit less impressive and somewhat unstructured.
In addition, there are only about 50 or so cluster members, spread out over 12 light
years of actual distance.
Compare M50 and M47, and let me know your thoughts from observing these open clusters
in the southern sky.
Observing tip: 50 mm aperture binoculars have more than 50 times the area of the fully dilated
human pupil, allowing us to see 2 to 4 magnitudes fainter with them than no optical aid.
Their 5 to 7 degree fields of view make them well-suited to viewing comets, large star
clusters, and sweeping the Milky Way.
Along The Ecliptic: Five planets are within 20 degrees of the Sun this week, which leaves
us only with Jupiter still near the Hyades in Taurus, with a nice double moon transit
occurring on the 9-th, and Saturn rising ever higher in the evening sky, hitting the sweet
spot of 20 degrees altitude by midnight this weekend.
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.