Skywatcher's Guide: August and September 2022

Skywatcher's Guide written by: Lucas Snyder (Flandrau Planetarium Operator)

Navigation

• Stars and Constellations
• Solar System
• Calendar of Night Sky Events
• Deep Sky
• Frequently Asked Questions

Stars and Constellations

In August we can still see part of the spring sky at the beginning of the night after sunset. The bright star Spica in the constellation Virgo is low in the west-southwest. A little higher in the west is even brighter Arcturus in the constellation Boötes. The easily recognizable Big Dipper (Ursa Major) is also visible in the northwest. You can use two stars in the end of the bowl to find Polaris, the north star, which is the end of the handle of the Little Dipper (Ursa Minor). Next, high in the middle of the sky we see the summer constellations, with the three bright stars of the Summer Triangle being the most prominent. Vega is the highest and brightest of the three, with Deneb below towards the east and Altair to the southeast. Then Scorpius with the bright star Antares is visible to the south-southwest, and the "teapot" of Sagittarius is nearby towards the south. The summer Milky Way is prominent this time of year stretching all the way across the sky from south-southwest to north-northeast. Next, the fall sky is beginning to rise in the east at the beginning of the night. The "great square" of Pegasus is low towards the east and Andromeda is adjacent to the northeast. Cassiopeia is a little higher in the northeast, and appears as a "W" this time of year.

In September, Boötes is now low in the sky towards the west-northwest.  The Big Dipper is also very low in the northwest.  Polaris and the Little Dipper are of course still in the North.  Now Scorpius is low in the southwest, and we can see the Sagittarius "teapot" in the south-southwest.  The Summer Triangle is still up in the middle of the sky, and the summer Milky Way is still a prominent streak across the sky.  Next, Pegasus and Andromeda are higher in the east, and you might be able to find the Andromeda Galaxy. Cassiopeia is higher in the northeast and is starting to rotate to a "3" orientation. Finally, below that you may see Perseus along the horizon at the beginning of the night.

Interesting Stars Visible in August and September (during observatory hours)

[Return to Top]

Solar System

Mercury emerges from behind the Sun at the beginning of August, and will be visible in the evening sky until mid-September.

Venus is getting lower in the eastern sky each morning before sunrise.

Mars is getting higher in the morning sky before sunrise, moving through the constellation Taurus.

Jupiter rises earlier each evening, eventually coming up at sunset at the end of September.

Saturn will rise at sunset in early August and will appear higher in the east each evening.

Jupiter Great Red Spot Transits during August and September (during observatory hours)

Note: The GRS is visible on the disk of Jupiter for 50 minutes before and after meridian transit time.

[Return to Top]

Calendar of Night Sky Events

[Return to Top]

Deep Sky

There are many deep sky objects we can see since the summer Milky Way is high in the sky.  There are many open star clusters that can be seen with only binoculars scanning this part of the sky.  For example we have the Butterfly Cluster (M6) and Ptolemy's Cluster (M7) near the tail of Scorpius.  Further north there is the Wild Duck Cluster (M11) in the faint constellation of Scutum between Sagittarius and Aquila.  There is also the asterism of the Coathanger between Aquila and Cygnus in the fainter constellation of Vulpecula.  Next, heading towards the west we can see the Coma Star Cluster in the constellation of Coma Berenices, which is even visible naked-eye.  The Pleiades (M45) will be visible later in the night, after midnight.

There are a several globular clusters we can see as well, as the center of our galaxy is the highest it gets for the year.  Near the bright star Antares in Scorpius lies the globular cluster M4.  In Sagittarius we also have the Teapot Cluster (M22).  Of course we have the famous Hercules globular (M13) high in the east.  Also, M15 is visible in the east near the head of Pegasus.

For nebulae, we have several in the plane of the galaxy, one of which is the Swan Nebula (M17) in Sagittarius, also known as the Omega Nebula.  There is also the Lagoon Nebula (M8) nearby and the North America Nebula (C20) further north in Cygnus.  For planetary nebulae we have the Ring Nebula (M57) in Lyra, the Dumbell Nebula (M27) in Vulpecula, and the Blue Snowball (C22) in Andromeda.

And now the galaxies:  Although the Big Dipper is getting lower in the sky, you may still be able to find some of the galaxies in this part of the sky.  We have the Whirlpool Galaxy (M51) and the Pinwheel Galaxy (M101) near the handle, and the Cigar Galaxy (M82) and Bode's Galaxy (M81) near the bowl.  The spectacular Andromeda Galaxy (M31) is now coming up in the northeast, along with the nearby Triangulum Galaxy (M33).

Interesting Deep Sky Objects to Observe during August and September (during observatory hours)

[Return to Top]

Frequently Asked Questions

What's so special about the James Webb Space Telescope?  Is it that much better than Hubble?

By now you've probably seen some amazing images from the newly launched James Webb Space Telescope.  But you may remember the amazing images taken by Hubble and wonder whether there's really that much improvement.  Well, there are a couple reasons why James Webb goes above and beyond even the amazing Hubble.

First is the size.  Hubble's main mirror is 2.4 meters across, which gives it a collecting area of 4 square meters.  This is bigger than any amateur telescope on Earth and even many professional ones as well.  But James Webb is 6.5 meters across and has an area of over 25 square meters!  That means it takes less than 1/6 as much time to create an image as Hubble and it has over 2.5 times the resolution.  So it can get more detail in less time, allowing us to see farther, fainter, and smaller things in our universe.

Next is wavelength.  Hubble is mainly designed to see in the visible part of the spectrum, the same as what human eyes can see.  It can extend a little into the ultraviolet and infrared, but not that much.  James Webb, on the other hand, can see much deeper into the infrared, overlapping the visible spectrum only slightly.  The reason this is important is that only very hot objects glow in the visible and ultraviolet parts of the spectrum, whereas just about every object gives off infrared light.  So some objects, no matter how long we might look, would be invisible to Hubble.  James Webb allows us to see things like exoplanets, asteroids, dust clouds, and potentially much more than what we have been able to see before.

To be fair, there are other infrared telescopes, but until now the largest one that can see similar wavelengths as James Webb is 3.5 meters across (the UK Infrared Telescope in Hawaii).  Besides size, though, the other main advantage is that it is in space.  Putting telescopes in space means we don't have to deal with the effects of Earth's atmosphere.  What we call twinkling may seem pretty to our eyes, but for astronomers, it causes our images to be blurry.  Putting a telescope in space makes our images much sharper than what we can get from the ground.  (Side note:  There is a technique called adaptive optics that can cancel out effects of atmospheric turbulence, but we still need very large telescopes to reach the resolution of Hubble.  I don't believe any ground-based telescopes can reach the resolution of James Webb even with adaptive optics.)

Another factor to be considered is that certain molecules in Earth's atmosphere block many infrared wavelengths.  In particular, water vapor absorbs several bands of the infrared spectrum, hiding that light from telescopes on the ground.  So having James Webb in space effectively removes a big curtain from our view of the infrared cosmos.  James Webb is certain to reveal a treasure trove of information about our universe that we can only dream about today.

If you have any questions you'd like me to answer in the next issue of SWG, please let me know.  I'm also happy to take suggestions or comments, and also pictures if you'd like to send them.  Happy viewing!

[Return to Top]

Date of publication: 2022