Aquarius the Water Bearer ranks as the 10th largest constellation in area. With a total of 980 square degrees, it is located in the southern part of the night sky between the constellations Capricorn on the right and Pisces on the left. The asterism consists of ten stars appearing as two side by side backward commas. The alpha star named Sadalmelik shines at magnitude 3.2 is a yellow G type star located some 750 light-years from us.

With luminosities some 3,000 times that of our Sun, this star is classified as a rare modest supergiant. Its enormous girth indicates it is starving for fuel and is dying. This starvation causes the star to balloon out to about the orbit of Jupiter if it were in our solar system. But some five billion years from now, our Sun will be following this same fate and expand to the orbit of Mars.

The beta star Sadalsuud is located ten degrees from Sadamelik. By coincidence, this G class supergiant star is also going through its final stages of life. It measures 50 solar diameters across (10 diameters less than Sadamelik and has a surface temperature of 5,800 K or the same as our Sun. The star Gliese 876 is the parent to four planets and is one of the closest groups of planets to us. First, locate the magnitude 3.2 star Delta Aquarii in the southern portion of the constellation’s boundary. Using the chart, Gliese 876 should be about two degrees north of this star. At only 15 light-years away, Gliese 876 shines at about tenth magnitude and is a target of star parties or just showing off to the neighbours.

Moving back to the western section of Aquarius, relocated Sadalsuud and then move your scope about nine degrees southwest until you come across the Saturn Nebula. Catalogued as NGC 7009, the Saturn Nebula has an overall brightness of magnitude 8.0 with a magnitude 11.5 central star. Its name comes from the somewhat resemblance of our famous ringed planet as seen almost edge-on. This stellar corpse that was once a thriving star is located about 2,500 light-years from us.

Continue almost in the same direction for another three degrees to the small and distant M72. The cluster is estimated to be 106 light-years width with a population of about 100,000 suns. Appearing grayish in colour, M72 resides some 53,000 light-years from us and is one of the most remote globular clusters. For a challenge, try to spot a magnitude 14.3 galaxy. Catalogued as UGC 11814, this smudge only measures .9 arc minutes wide. Good luck with this one.   

At the beginning of the month, the lonely planet Saturn sets just before 10 p.m. local time. Although Jupiter is technically in the west, it is low and soon lost in the Sun’s glare. Venus still owns the east with tiny Mars just below and to the left of it.

Of the dozen or so comets that are paying a visit to the inner solar system, comet C/2017 O1 ASAS-SN is an easy binocular or small telescope target as it heads north. Discovered on July 19, 2017, by the automated sky survey, the comet was a faint magnitude 15.3 but quickly brightened to magnitude 10 in a few days. Currently, at magnitude 9.4, the comet is estimated to peak at magnitude 8 on October 14. Once the moon is gone, you should have a great opportunity to image this comet at its brightest. 

The full Hunter’s Moon will occur on October 5 and the new moon will be on October 19. With the moon absent, try to locate the zodiacal lights in the east before astronomical twilight begins. This ghostly light is created by sunlight reflecting off interplanetary dust. The slanted triangular light can reach some forty degrees in height with Venus and Mars tucked inside. Zodiacal lights are seen close to autumn and spring.

Until next month, clear skies everyone.

Gary Boyle

Twitter: @astroeducator