Skywatcher's Guide: June and July 2024

Stars and Constellations

In June, the spring sky is now prominent overhead, along with the familiar Big Dipper.  The Big Dipper is high in the north, and the two stars at the end of the bowl can be used to find Polaris, our north star.  Also, the handle can be used to "arc to Arcturus", a bright star in the constellation Boötes. Then Hercules is just below towards the east.  Next, Leo the lion is very high in the west, with the constellation Virgo nearby to the south.  A few winter constellations are still visible, now very low in the west.  Castor and Pollux, the heads of Gemini the twins, are the most prominent, to the west-northwest.  The summer sky is now just starting to come up at the beginning of the night.  The bright star Vega in the constellation Lyra the harp is towards the east-northeast.  In the southeast we have the constellation Scorpius the scorpion, with the bright star Antares.  Further to the south we can also see the constellations of Centaurus and Lupus the wolf right along the horizon.

In July, the last of the winter constellations are now gone, and the spring constellations are beginning to head to the west.  The summer constellations are now mostly up in the east.  We can easily see all three stars in the Summer Triangle, Vega being the highest in the east-northeast, Deneb a little lower to the northeast, and Altair to the east.  To the southeast we can see the Teapot of Sagittarius near the tail of Scorpius.  Also, to the north-northeast we can see the W of Cassiopeia the queen.

Interesting Stars Visible in June and July (from 7-10 pm)

Name / Designation Apparent Magnitude
(lower = brighter)
Arcturus -0.05 36.7  
Vega 0.03 25  
Capella 0.08 42  
Procyon 0.4 11  
Altair 0.76 17  
Spica 0.98 262  
Pollux 1.16 38  
Markab 1.25 140  
Deneb 1.25 3230  
Regulus 1.36 77 means "Little King"
Castor 1.58 52  
Polaris 1.97 431  
Alpheratz or Sirrah 2.07 97  
Denebola 2.14 36.2  
Enif 2.38 670  
Albireo 3.2 / 5.8 & 5.1 390 / 380  possibly a triple star system
Eta Cassiopeiae 3.5 / 7.4 19 480 yr orbit

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Solar System

Mercury passes behind the Sun in mid-June but will be visible in the evening sky for much of July.

Venus passes behind the Sun in early June but will be visible in the evening sky by the end of July.

Mars is getting higher in the morning sky, moving from Pisces, through Aries, and into Taurus.

Jupiter rises in the morning sky beginning in early June and is in the constellation Taurus.

Saturn is in Aquarius, rising in the early morning in June and the late evening in July.

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Calendar of Night Sky Events

Date Event
06/04/24 Appulse of Mercury and Jupiter. — Separated by 0.1°.
06/04/24 Venus at superior conjunction. — Passing behind the Sun.
06/06/24 New Moon.
06/13/24 First Quarter Moon.
06/14/24 Mercury at superior conjunction. — Passing behind the Sun.
06/17/24 Appulse of Mercury and Venus. — Separated by 0.9°.
06/20/24 Earth at northern solstice. — Beginning of our Summer.
06/21/24 Full Moon.
06/28/24 Last Quarter Moon.
07/04/24 Earth at aphelion. — Our farthest distance from the Sun.
07/05/24 New Moon.
07/13/24 First Quarter Moon.
07/15/24 Appulse of Mars and Uranus. — Separated by 0.5°.
07/21/24 Full Moon.
07/21/24 Mercury at greatest eastern elongation. — Visible in the evening sky.
07/22/24 Pluto at opposition. — Best time to look for this dwarf planet.
07/27/24 Peak of Delta Aquariids meteor shower.
07/27/24 Last Quarter Moon.

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Deep Sky

There are several open star clusters we can see this time of year. First, Coma Berenices (Bernice's Hair) is high in the west near the tail of Leo. Next, there is the Ptolemy cluster (M7) and the Butterfly (M6) in the southeast near the tail of Scorpius. Also nearby is the Wild Duck (M11) in the constellation of Scutum.

Now that the Milky Way is coming up, there are several globular clusters we can see. M3 is high in the west, in the constellation Boötes. Nearby, the famous Hercules Globular (M13) is high in the east. We also have M5 high in the south in the constellation of Serpens. Finally, for those with a clear horizon, the amazing Omega Centauri (C80) is visible low to the south.

For nebulae, we can see the Swan (M17), the Lagoon (M8), and the Trifid (M20) to the southeast in the constellation Sagittarius. The Eagle (M16) is nearby in the constellation of Serpens. The North America nebula is also in the northeast in Cygnus. For planetary nebulae, we have the Owl (M97) in Ursa Major high in the northwest. We also have the Dumbbell (M27) in the west-northwest in the constellation of Vulpecula and the Ring (M57) nearby in Lyra.

And now the galaxies: In Ursa Major to the northwest we have Bode's Galaxy (M81) and the Cigar Galaxy (M82), close enough to be seen together in a low-power telescope. Nearby in the constellation Canes Venatici we have the Whirlpool (M51), which is a pair of colliding galaxies. The Pinwheel Galaxy (M101) is also nearby near the handle of the Big Dipper. Then the Southern Pinwheel (M83) is to the southwest in the constellation Hydra. The Sombrero Galaxy (M104) is nearby in the constellation Virgo.

Interesting Deep Sky Objects to Observe during June and July (from 7-10 pm)

Designation Name Apparent Magnitude Apparent Size Distance
Messier 31 Andromeda Galaxy 3.4 3° x 1° 2,900,000 spiral galaxy
Messier 44 Beehive Cluster 3.7 95' 577 open cluster
Messier 3 (in Canes Venatici) 6.2 18' 34,000 globular cluster
Messier 27 Dumbbell Nebula 7.4 8' × 6' 1,250 planetary nebula
NGC 7009 Saturn Nebula 8 36" 2,400 planetary nebula
Messier 81 Bode's Galaxy 8.5 21' 12,000,000 spiral galaxy
NGC 3242 Ghost of Jupiter 8.6 25" 1,400 planetary nebula
Messier 57 Ring Nebula 8.8 1' 2,300 planetary nebula
Messier 82 Cigar Galaxy 9.5 14' 12,000,000 galaxy

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Frequently Asked Questions

How do we know what things are made of in space?

There are only a handful of places in our solar system where we've sent our robots to take samples and either analyze them on site or return them to Earth.  But there are other ways we can identify what things are made of without even having to go there.  Specifically, we use a technique called spectroscopy.

All matter in space (except dark matter) interacts with light by emitting it, absorbing it, and/or reflecting it.  This includes light not only in the visible part of the spectrum, but also in all the invisible parts, all the way from radio to gamma.  But not all wavelengths interact the same way.  Some are more likely to interact with certain materials than others, giving us a way to see what things are made of.

The most common element in space is hydrogen.  If you take a simple photo of a nebula, for example, it will have a pinkish glow to it.  But if you split that light into a spectrum, you'll see distinct emission lines at red, cyan, blue, and violet.  If you expand to other parts of the spectrum, there are also lines in the infrared and ultraviolet.  This specific arrangement of emission lines can be thought of as the "fingerprint" of hydrogen.  Every element and every molecule has a unique fingerprint that can distinguish it from everything else.  Fun fact: Helium was discovered in space before it was found on Earth because it had a fingerprint that we did not recognize from the known elements at the time.

Complicating this a bit is the fact that lines can shift depending on the motion of the source.  Objects moving towards us will have their lines shifted towards the blue end of the spectrum (a blue-shift), and objects moving away will have their lines shifted towards the red end (a red-shift).  The expansion of our universe was discovered by noticing a red-shift in nearly every galaxy we looked at.

So if there's something you want to figure out what it's made of, you can spread its light into a spectrum, compare it with the known spectra of various elements and molecules, and shift according to the object's speed.  This technique has allowed us to determine the makeup of the clouds of Jupiter, find evidence of water on Mars, and distinguish rocky and metallic asteroids.

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!

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Date of publication: 2024