Monthly Night Sky Report: October 2024

   Introduction

    September turned out to be a decent month for stargazers. The cooler temperatures were a huge plus, and northern Utah's skies remained relatively cloud-free. I wasn't able to see Comet Olbers or the Zodiacal Light, but I was able to enjoy views of the planets and constellations. 

    October will likely bring cooler weather and more clouds over Utah. Comet A3, mentioned last month, will continue to brighten as it approaches the Sun. As of this writing, the Blaze Star in Corona Borealis has yet to brighten in its nova event. The Orionid Meteor Shower returns during October's Full Moon, and for observers in the southern tip of South America or who can travel, there will be an annular solar eclipse.  

                      

Mercury

   During September, Mercury could be found in the morning sky before its conjunction with the Sun. After its conjunction with the Sun, Mercury will transition from a morning sky object to an evening object. Shortly after sunset, this tiny world can be seen above the western horizon if an observer has an elevated and clear view. Mercury will brighten throughout October but will not gain much, if any, altitude, making this a truly challenging object to spot. 

  

Venus

   Venus will continue to dominate the evening sky throughout the month. Gleaming brightly at -3.9 magnitude, I can easily spot Earth's evil twin, even from my obstructed view of the western sky. Venus can be used as a guide to find Mercury by forming a line between it and where the Sun had set. Mercury should be visible along this line, but I doubt this tiny world will be detectable due to its elevation. Lying just 5° away, a thin crescent Moon will join Venus on the 5th. By the middle of the month, Comet A3 will move to the evening sky and be visible to the upper right of Venus. A pair of binoculars or a telescope will likely be required, but as comet brightness is so unpredictable, an observer may be able to see the comet without visual aid. 

    

Mars

    Mars will continue to brighten throughout October as it nears opposition in early 2025. The Red Planet can be seen rising above the Rocky Mountains close to 1:00 AM as the month starts and about two hours earlier by the end of the month. It will continue to be found in good company with the redness of Aldebaran in Taurus and Betelgeuse in Orion. A fainter part of the Milky Way band can be seen between Mars and Betelgeuse if an observer is away from heavy light pollution. Near the end of October, observers can see some notable surface features of Mars. On the 26th, Olympus Mons, the largest known volcano in the solar system, can be seen. On the 31st, Valles Marineris, the largest known canyon in the solar system, and Tharsis Ridge may be seen. Of course, a telescope (the larger, the better) or camera attached to a telescope will be required. The Moon will pass close by on the 23rd.   

Jupiter

Saturn

    As in September, Jupiter will remain between Mars and Aldebaran throughout October. This gas giant should be easy to spot as it will be the brightest natural object in the sky next to the Sun, Moon, and Venus. Several Galilean Moon transits can be viewed throughout the month, so be sure to check out the Moons of Jupiter & Saturn app for Android or JupiterMoons for Apple devices. The Great Red Spot may also be seen at specific times depending on the observers' location, which the resources mentioned above can also be helpful. An observer will need a four-inch (100 mm) telescope or larger to view the transits and the Great Red Spot. A nearly Full Moon will join Jupiter on the 21st.      

    Saturn reached opposition in early September, bringing the best time of the year to view this planet. Of course, that should not deter observers from seeking out the ringed planet in October! Views of Saturn's ring system will still be worth checking out this month.  A small telescope can easily show this sought-after feature, as can Titan, the largest moon of Saturn and the second largest in the solar system. The Earth's own moon will join Saturn on the 14th. The Moons of Jupiter & Saturn app for Android or Saturn's Satellites web app can be used to find the locations of several of Saturn's moons. For those with Apple devices,  JupiterMoons and SaturnMoons should offer similar results.   

       

Neptune

Uranus

    

    Uranus will continue to be found close to the Pleiades throughout October. This ice giant can be found to the lower right of the Seven Sisters if viewed shortly after sunset and nearly directly below if viewed in the early morning hours. A pair of binoculars, which provide the best views of the Pleiades, or a telescope will be required to see Uranus. A nearly Full Moon can be found nearby on the 19th. Uranus will reach opposition in November.

    Neptune will continue to trail behind Saturn throughout October. A nearly Full Moon will pass by this most distant ice giant on the 15th. Gazing at this planet through a telescope will reveal a bluish color, distinct from the background stars.      

Blaze Star, Orionids, Comet A3

    As of this writing, astronomers are still waiting for a star known as T Coronae Borealis, or the Blaze Star, to go nova. As mentioned in my September post, the Blaze Star is actually two stars, a white dwarf and a red giant. The white dwarf, a star that has used up all of its own material, is siphoning material from its companion. When the white dwarf has gathered enough material, which increases its pressure and heat, a thermonuclear explosion known as a nova will happen. This event occurs, on average, every 80 years. Before the nova event, this binary star system, glowing dimly at magnitude 10.13, is undetectable by the unaided human eye. When the nova event does occur, the Blaze Star will brighten to about 2.0 magnitude, roughly the same brightness as Polaris. The North Star is bright enough to be seen from my light-polluted skies near Salt Lake City. The Blaze Star belongs to Corona Borealis, the constellation between Boötes and Hercules in the night sky. These constellations are currently found in the west after sunset. An observer's best bet for finding the Blaze Star is to first locate Arcturus, a bright red giant star close to the western horizon, and Vega, a bright blue-white star located nearly overhead as the Sun sinks below the horizon. Arcturus is the brightest star in the northern hemisphere, followed by Vega during summer and early fall, so they should be easy to find. The Blaze Star is located about halfway between these stars. 

    This year, the Orionid Meteor Shower will peak on the 21st, closely coinciding with the Full Moon. The brightness from the Moon will undoubtedly obscure all but the brightest meteors on the peak date. Fortunately, this shower is active between the 2nd of October and the 7th of November, so interested observers should try to spot an Orionid Meteor in the week before or after the Full Moon. If the Moon did not interfere with these meteors, the observer could expect to see about 20 meteors per hour on its peak date. As the name suggests, the Orionid Meteor Shower appears to radiate from the constellation of Orion, which rises above the Rocky Mountains shortly after midnight on the 21st.

    Comet A3 (C/2023 Tsuchinshan-ATLAS) is currently visible in the morning twilight before sunrise. Glowing between magnitude 2.72 and 2.55 during the first week of October, Comet A3 would be visible with the unaided eye if not for the rising Sun's glow. By the 9th, A3 will have transitioned from the morning sky to the evening sky. As the month progresses, A3 will pull away from the Sun from our vantage point, moving higher above the western horizon, making it easier to spot. Comet A3 will be visible with the unaided eye if an observer is at a dark sky location and if it survives its close approach to the Sun. Either way, a pair of binoculars or a telescope will help an observer get more detail from its coma while a camera (any camera!) will help get an image of its long tail extending away from the Sun. As mentioned, a dark sky and a clear view of the eastern horizon during the first week of October or the western horizon for the rest of the month will significantly enhance the views and chances of spotting this visitor.       

Monthly Breakdown

October 02: New Moon 🌑
October 05: Moon passes within 3° of Venus
October 10: First Quarter Moon 🌓

October 14: Moon passes within 0.1° of Saturn

October 15: Moon passes within 0.6° of Neptune 

October 17: Full Moon 🌕
October 19: Moon passes within 4° of Uranus
October 21: Orionid Meteor Shower peaks

October 21: Moon passes within 6° of Jupiter

October 23: Moon passes within 4° of Mars 

October 24: Last Quarter Moon🌗

 

         

Now get outside and look up!

Planet images were taken by NASA.

Andrew vs. the Cosmos image was taken by Jeff Greenland.

The Milky Way and Trees image was taken by Andrew Greenland.

Orion, Taurus, and Pleiades image was taken by Andrew Greenland.

                

                

Midmonth Check-In: September 2024 and Dwarf Planets

       

  Introduction and Monthly Reminders   

    September has started off cooler and much more pleasant to be outdoors. Northern Utah experienced some decent-sized thunderstorms and a cold front, which dropped the temperatures by over 20º F. The cold front brought heavy winds, which made the atmosphere unstable, creating poor telescope views and astrophotography image quality unless the tripod was securely mounted. Before the storms rolled through, I was able to capture some great images of the night sky that I will share in a future post.

    The remainder of the month is projected to remain cool with a chance of more rain storms. Astronomers will still be able to enjoy Neptune reaching opposition and the zodiacal light, weather permitting. Observers in Utah can also watch the Moon occult Neptune in the early morning hours on the 18th.

Dwarf Planets

    Many individuals were upset about the reclassification of Pluto from the ninth planet to a dwarf planet in 2006. Since its discovery in 1930, Pluto had not even completed a full orbit of the Sun before this demotion occurred. Some of the disgruntled created memes, t-shirts, and other propaganda depicting how Pluto went from angry to sad to lonely for not being considered a planet. Fortunately for Pluto, it is not alone! There are currently four other dwarf planets orbiting our Sun, and there are over 100 other likely candidates. But why was Pluto demoted, and what distinguishes a dwarf planet from a regular planet?

    After the discovery of Pluto in 1930 and prior to the reclassification of it as a dwarf planet in 2006, several other objects were discovered to be similar in size to Pluto. The previous ninth planet is actually smaller than the Earth’s own Moon and a few of the Moons of Jupiter and Saturn. However, size is not the only thing that distinguishes dwarf planets from other planets. A planet must orbit its parent star like the Earth orbits the Sun. A planet must be relatively round, and its gravity must be sufficient enough to have cleared its orbit of all other objects that are similar in size. Pluto and the other dwarf planets orbiting the Sun failed the last criteria of clearing their orbit of similarly sized objects. 

    The International Astronomical Union (IAU) is a worldwide organization of astronomers. It is the group that votes on and decides what makes a planet a planet and what makes dwarf planets what they are. The closest dwarf planet to the Sun is Ceres. It resides in the asteroid belt between Mars and Jupiter. It was discovered in 1801 and was thought to be an asteroid. Fast forward 214 years when the Dawn spacecraft from NASA visited this rock to determine its size and composition. Ceres makes up about a quarter of the mass in the asteroid belt, is primarily spherical but is roughly 14 times smaller than Pluto. Given this information, Ceres was promoted from an asteroid to a dwarf planet. 

    Pluto is the most famous of the five dwarf planets and lies, on average, 40 AU from the Sun. This distance places this dwarf planet in the Kuiper Belt. It was visited by the New Horizons mission in 2015. This mission was able to capture several images of Pluto, including the one of the heart shaped feature on its surface, seen below. 

The heart of Pluto was taken in 2015.

    Even at the great distance of 40 AU, where it takes sunlight over 290 minutes to reach this dwarf planet, Pluto is the second closest dwarf planet to the Sun. One complete orbit of the Sun takes 248 Earth years while one day lasts about 6 Earth days. 

    Haumea is also located in the Kuiper Belt, orbiting the Sun at 43 AU. It was discovered in 2004 by two separate astronomy teams. Haumea is about the same size as Pluto but is oval shaped, much like a football. One year on this dwarf planet is about 285 Earth years. However, a day is only four earth hours, meaning Haumea is one of the fastest-rotating large-bodied objects discovered to date. Haumea is also the first object found in the Kuiper Belt to have a ring system.

    Makemake is about half the size of Pluto and resides in the Kuiper Belt, roughly 46 AU from the Sun. One year on Makemake is equal to 305 years on Earth, while a day is similar to an Earth day at 22 hours. Not much is known about this dwarf planet except that it is brownish in color, similar to Pluto.

    Eris is currently the fifth and last known dwarf planet in our solar system. It also resides in the Kuiper Belt at a distance of 68 AU. It takes Eris 557 Earth years to complete one orbit, but its day length is similar to Earth's at 25.9 hours. The discovery of Makemake and Eris made the IAU redefine the classification of planets, hence demoting Pluto to dwarf planet. For those upset by this demotion, remember that dwarf planets are planets, too!

    

 

    Check back soon for my next post!

    

Now get outside and look up!