Capricorn, Aquarius and a Lunar Eclipse

Moving eastward from the great Teapot of Sagittarius, we continue our voyage along the ecliptic to Capricornus – The Goat. This constellation takes up 414 square degrees of sky making it the 40th largest constellation. To date – nine planets have been found orbiting five stars in Capricorn. The stars that make up the asterism are of average brightness, running in the range of magnitude 2.8 to 4.5.

Deneb Algedi is the brightest sun and can be spotted to the far left side of the starry pattern. Pretty well a next door neighbour, this 39 light year white colour star has a spectral class of A5. It also has an unseen companion star that transits across Deneb Algedi’s disk every 1.023 days which drops its brightness by only .02 magnitudes. Deneb Algedi shines 85 times the luminosity of our Sun. Then we have the star named Dabih which is located on the far right corner of the asterism. This complex multiple star system is estimated to be 328 light years from us. What appears as a double star in a telescope is actually a family of five. Beta 1 is a third magnitude orange coloured spectral class K star. It also has a seventh magnitude companion as well as another star invisible to the human eye that orbits the primary every 8.7 days. Beta 2 is a magnitude 6 class “A” star with a second companion only 3 arc seconds away.

One of a few choice objects to hunt down is the globular cluster M30. Situated as most globular clusters around the nucleus of our Milky Way Galaxy, M30 lays some 28,000 light years away. With a visual magnitude of 7.2, this “snowball” of stars measures 12 arc minutes wide which relates to 90 light years in width and is a treat to observe in any telescope. NGC 6907 is a barred spiral galaxy with good structure. At an estimated distance of 121 million light years, this galaxy measures 3.4 by 2.6 arc seconds. NGC 6907 is located a little less than five degrees west of magnitude 3.2 Psi Capricorni.

Moving on to Aquarius – The Water Bearer takes up 980 square degrees of sky. Sadalsuud or Beta Aquarii has a magnitude of 2.9 and is the brightest star of Aquarius. This rare yellow super giant is located 540 light years from us. Its mass is six times that of our Sun and is 2,200 times more luminous. When looking at Sadalsuud in a telescope, you are gazing at a triple star system. One component measures magnitude 11.0 and is located 35 arc seconds from the Sadalsuud. The other star is a bit fainter at magnitude 11.6 and can be found 57.2 arc seconds from the main star.  

Two Messier objects call Aquarius home with the first located to the far western portion of the constellation. At an estimated age of 13 billion years, M2 is one of the oldest and largest globular clusters of the Milky Way Galaxy. It is located some 37,000 light years from us and 175 light years wide and contains about 150,000 suns including 21 variables. M2 is registered at magnitude 6.5 and can sometimes be glimpsed naked eye. This globular is located five degrees north of Sadalsuud.

As a sharp contrast from M2, M72 is a small and faint globular cluster. With its great distance of 53,000 light years away, M72 is on the other side of the Milky Way. M72 spans about 50 light years across and holds an estimated 100,000 stars. The Messier Catalog does post an entry for M73 with its position in the sky located to the left of M72. The area in question only shows four stars in a ‘Y’ formation. Moving on, we come across the Saturn Nebula (NGC 7009) and as the name depicts, this object takes on the iconic planetary shape which is easily seen in small telescopes and photographs. This greenish-yellow planetary nebula is located 2,400 light years away with a magnitude of 12.1. Its blue central dwarf star is thought to be a hot 55,000 K. The entire planetary measure 36 arc seconds in length.

We conclude our tour with the planetary nebula NGC 7293 aka the Helix Nebula. This object is very impressive in structure. The Helix has appeared on religious web sites and sometimes referred to as the “Eye of God”. NGC 7293 is only 450 light years away making it one of the closest planetary nebulas to Earth. Its apparent size in the sky is 16 by 28 arc minutes keeping in mind the full moon measures 30 arc minutes. Aquarius is also the current home to the farthest planet of our solar system. Neptune appears as a light blue fuzz ball and at magnitude 7.8 is too faint to be seen with the naked eye. Only a telescope can reveal its featureless disc. Because Neptune takes 165 years to complete one orbit around the Sun, Neptune will not be officially cross the Aquarius border until March, 2023. Neptune is located between Lambda and Sigma Aquarii.

For the past month or so Saturn was the only planet visible in the night sky. For those following the ringed planet, its visibility is coming to an end as it will sink in the dusk sky by month’s end. It will set 10:30 p.m. local time on the first of September and by 9:30 mid-month. But fear not, Venus and Mars have distanced themselves from the solar glare and are above the eastern horizon by 4 a.m. and you will begin to see Jupiter commencing mid-month. The new moon (lunation 1147) occurs on the 13th and the full Harvest moon slated for the 27 and yes it will be another so-called “super moon”. This will not be a normal Harvest moon but an eclipsed Harvest moon.

The geometry of the Sun, Earth and Moon will be just right to produce a total lunar eclipse. The entire event will be seen from the eastern half of Canada. The left side of the moon will begin to slide into the Earth’s shadow on September 27 at 9:07 p.m. eastern. Mid eclipse or the darkest the moon will be occurs at 10:47 p.m. and exiting the shadow at 12:27 a.m. This will be the last eclipse until the year 2018. And lastly the fall equinox occurs on September 23 at 4:21 a.m. eastern or 8:21 UT.

On a personal note, it was this month back in 1965 that I was introduced to astronomy. Returning to elementary school at the age of eight for a new school year, I was strolling through the library to see what new books arrived. I happened to come across the old “How and Why Wonder Book of Stars. Thumbing through the pages I was astonished by the drawing of our Earth and Sun only to read 109 Earths fit across the Sun’s equator and more than a million would fit inside. Then there were distances and colours of stars that kept me coming back for more. At the age of 13, I bought my tiny refracting telescope from a catalogue store in Montreal named Consumer’s Distributing which over the years led to bigger and better telescopes. 

Technology has changed greatly in the past half century. But even with the high tech telescopes and CCD cameras available, one should not get too involved in setting up that perfect image and just look up. Even with an observatory I still find myself looking at the whole sky with binoculars or naked eye to drink in the same star light that fueled my excitement when I was young. Sharing the wonders of the night is something we all love to do. Enjoy the beauty of the night. It’s a wonderful classroom. 

Until next month, clear skies everyone.

Gary Boyle

Twitter: @astroeducator

eNews date: 
Tuesday, September 1, 2015