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Kiss the Sky Tonight -- Month of October 2020
A spectacular swarm of stars, M15 was discovered in 1746 by Jean-Dominique Maraldi, an Italian astronomer on the hunt for comets. This globular cluster is one of the densest ever discovered, with very hot blue stars and cooler orange stars becoming more concentrated toward its bright core. M15 is located in the constellation Pegasus 33,600 light-years from Earth. Shining with an apparent magnitude of 6.2, the cluster can be spotted with a pair of binoculars. The best time to observe it is in October. M15 was the first globular cluster known to host a planetary nebula (the gaseous shell of a dying star). This nebula, Pease 1, was detected in 1928 by Francis G. Pease and is one of only four planetary nebulas known to exist within a globular cluster. In this image, Pease 1 appears as the large, bright blue object to the left of the cluster’s center. This cluster has also been found to host a rare type of black hole at its center: an intermediate-mass black hole. Supermassive black holes are found at the center of galaxies and can be billions of times more massive than the sun. More diminutive “stellar” black holes, on the other hand, are on the order of 10 solar masses. The black hole thought to exist at the center of M15, however, is 4000 times the mass of the sun. Hubble captured this image of M15’s core using observations in visible, infrared and ultraviolet light. [Video Credits: NASA, JPL – Caltech, and the Office of Public Outreach – STScI] [Image Credit: NASA, ESA]
Kiss the Sky Tonight -- Month of October 2020
Welcome to the night sky report for October 2020 -- Your guide to the constellations, deep sky objects, planets, and celestial events that are observable during the month. In October, Pegasus, the flying horse of Greek myth, becomes increasingly prominent in the southeastern sky. Look for M15 (NGC7078) and NGC7331. This October also brings a Harvest Moon and a Blue Moon. Plus look for Mars at any time of the night. The night sky is truly a celestial showcase. Get outside and explore its wonders from your own backyard.
The crisp, clear nights of October are full of celestial showpieces for the backyard sky gazer.
Face southeast after dark to find Pegasus, the flying horse of Greek myth, soaring high into the sky. The prominent square of stars that forms the body makes Pegasus a good guidepost for the autumn sky. Along the western side of the Great Square of Pegasus lies the star 51 Pegasi. It is notable as the first Sun-like star discovered to harbor an orbiting planet.
Farther west, near the star Enif, which marks the horse’s nose, lies an entire city of stars: the globular star cluster M15. Backyard telescopes show a grainy, concentrated sphere of light. NASA’s Hubble Space Telescope shows a stunning globe of ancient stars with many red giants. M15 is one of the densest globular star clusters known in the Milky Way galaxy.
Near the Great Square resides an even larger star city: the galaxy NGC 7331. In a telescope, the nearly edge-on spiral galaxy appears as an elongated smudge of faint light. The Hubble view shows that NGC 7331 is a galaxy very similar in size and structure to our own. NASA’s Spitzer Space Telescope’s view of the galaxy, which highlights infrared light, reveals a ring of dust circling the galaxy’s center at a radius of nearly 20,000 light-years. Spitzer measurements suggest that the ring contains enough gas to produce four billion stars like the Sun.
The brightest star of the Pegasus Great Square, named Alpheratz, marks the head of the princess Andromeda. Beside the Andromeda constellation is M31, the Andromeda Galaxy. Visible in dark skies as an elongated patch of light, the galaxy, at 2.5 million light-years distant, is the farthest object that can be seen with the unaided eye.
NASA’s GALEX mission imaged the ultraviolet light from the Andromeda Galaxy. The image shows its core and spiral arms traced by hot, massive, young blue stars and dark dust lanes. Andromeda is the nearest large galaxy to our own. Studies indicate that Andromeda is approaching and will collide and merge with the Milky Way more than four billion years from now.
The Andromeda galaxy is our Milky Way's largest galactic neighbor. The entire galaxy spans 260,000 light-years across. Andromeda is a spiral galaxy like our own Milky Way, but a bit larger. The light entering your eye when you observe Andromeda left that galaxy 2.5 million years ago when early hominids were just beginning to walk upright here on Earth.
Most of Andromeda's light comes from its bright central core, which is densely packed with bright stars. Thus it appears as a faint, fuzzy patch on the sky with a somewhat brighter spot near the center. Because it's somewhat faint, binoculars or a telescope are recommended, and it is best viewed on nights without a bright Moon.
This month brings not just one, but two full Moons, at the beginning, and at the end of the month. The Harvest Moon – the one that peaked on October 1 – is the name for the full Moon that occurs closest to the September equinox (One of two days per year when day and night are of equal length). Most years the Harvest Moon falls in September, but every few years it shifts over to October. The name traces back to both Native American and European traditions related, not surprisingly, to harvest time.
At the end of October, on the 31st, we'll enjoy a second full Moon. When there are two full Moons in a month, the second is often called a Bue Moon. (There's another, more traditional definition of a Blue Moon, but this is the most well known). Note that this is the only two-full-moon month in 2020.
This month, Mars is in opposition. During opposition, Mars and the Sun are on directly opposite sides of Earth. From our perspective on our spinning world, Mars rises in the east just as the Sun sets in the west. Then, after staying up in the sky the entire night, Mars sets in the west just as the Sun rises in the east. Since Mars and the Sun appear on opposite sides of the sky, we say that Mars is in "opposition."
Oppositions of Mars happen every 26 months. The racetrack model of planetary orbits explains why. Earth and Mars are like runners on a track. Earth is on the inside, Mars is on the outside. Every 26 months, speedy Earth catches up to slower Mars and laps it. Opposition occurs just as Earth takes the lead.
If Earth and Mars followed perfectly circular orbits, opposition would be as close as the two planets could get. But because planetary orbits are elliptical, not all oppositions are the same. An opposition can occur anywhere along Mars' orbit. Every 15 or 17 years, opposition occurs within a few weeks of Mars' perihelion (the point in its orbit when it is closest to the Sun). This year, Mars opposition occurs on October 13, 2020.
Enjoy the patterns of stars, star clusters, galaxies, and planets on clear October nights.
The night sky is always a celestial showcase. Explore its wonders from your own backyard.
The following Deep Sky Objects are found in constellations that peak during the month. Some can be viewed with a small telescope, but the majority will require a moderate to large telescope. The following is adapted from my personal viewing list: "The Guy Pirro 777 Best and Brightest Deep Sky Objects."
NGC 205 Galaxy M110 Herschel 400 H18-5 Satellite of Andromeda
NGC 221 Galaxy M32 Satellite of Andromeda
NGC 224 Galaxy M31 Andromeda Galaxy
NGC 404 Galaxy Herschel 400 H224-2
NGC 752 Open Cluster C28, Herschel 400 H32-7
NGC 891 Galaxy C23, Herschel 400 H19-5
NGC 956 Open Cluster P123
NGC 7640 Galaxy P218
NGC 7662 Planetary Nebula C22, Herschel 400 H18-4 Blue Snowball Nebula
NGC 7686 Open Cluster Herschel 400 H69-8
IC 10 Galaxy P77
IC 59 Diffuse Nebula P21 - Gamma Cassiopeiae Nebula (West)
IC 63 Diffuse Nebula P22 – Gamma Cassiopeiae Nebula (East)
IC 166 Open Cluster P217
IC 1795 Diffuse Nebula P122
IC 1805 Emission Nebula P2 Heart Nebula
IC 1848 Emission Nebula P3 Soul Nebula
IC 1871 Diffuse Nebula P136
NGC 103 Open Cluster P137
NGC 129 Open Cluster Herschel 400 H79-8
NGC 133 Open Cluster P138
NGC 136 Open Cluster Herschel 400 H35-6
NGC 146 Open Cluster P204
NGC 147 Galaxy C17 Satellite of Andromeda
NGC 185 Galaxy C18, Herschel 400 H707-2 Satellite of Andromeda
NGC 189 Open Cluster P5
NGC 225 Open Cluster Herschel 400 H78-8 Sailboat Cluster
NGC 278 Galaxy Herschel 400 H159-1
NGC 281 Emission Nebula P4 Pacman Nebula
NGC 381 Open Cluster Herschel 400 H64-8
NGC 436 Open Cluster Herschel 400 H45-7
NGC 457 Open Cluster C13, Herschel 400 H42-1 Owl Cluster
NGC 559 Open Cluster C8, Herschel 400 H48-7
NGC 581 Open Cluster M103
NGC 609 Open Cluster P219
NGC 637 Open Cluster Herschel 400 H49-7
NGC 654 Open Cluster Herschel 400 H46-7
NGC 659 Open Cluster Herschel 400 H65-8
NGC 663 Open Cluster C10, Herschel 400 H31-6
NGC 1027 Open Cluster Herschel 400 H66-8
NGC 7635 Diffuse Nebula C11 Bubble Nebula
NGC 7654 Open Cluster M52
NGC 7788 Open Cluster P139
NGC 7789 Open Cluster Herschel 400 H30-6 White Rose Cluster
NGC 7790 Open Cluster Herschel 400 H56-7
NGC 7795 Open Cluster P23
NGC 7078 Globular Cluster M15
NGC 7217 Galaxy Herschel 400 H207-2
NGC 7331 Galaxy C30, Herschel 400 H53-1
NGC 7448 Galaxy Herschel 400 H251-2
NGC 7457 Galaxy P173
NGC 7479 Galaxy C44, Herschel 400 H55-1
NGC 7814 Galaxy C43
NGC 488 Galaxy Herschel 400 H252-3
NGC 524 Galaxy Herschel 400 H151-1
NGC 628 Galaxy M74
NGC 676 Galaxy P175
NGC 55 Galaxy C72
NGC 134 Galaxy P116
NGC 253 Galaxy C65, Herschel 400 H1-5 Sculptor Galaxy
NGC 288 Globular Cluster Herschel 400 H20-6
NGC 300 Galaxy C70
NGC 613 Galaxy Herschel 400 H281-1
NGC 7507 Galaxy P117
- NGC 7513 Galaxy - Paired with P117
NGC 7793 Galaxy P61
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