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July is a busy month to observe the sky. Not only are five luminous planets visible, but three comets and a newly discovered nova are also observable. And it all starts with a bang on Independence Day
Fireworks illuminate the skies over Duluth, Minnesota, on July 4th.
Bob King
Many of us watch the fireworks on July 4th. The fact that most of the elements used to make these colorful explosions originate in the violent and explosive death of massive stars proves that the universe has a sense of unpleasant humor.
Think about it. The sulfur, oxygen and carbon of the fuel, as well as iron, strontium, barium and copper which give the sparks their gold, red, green and blue colors, were created and released when massive stars self-annihilated. What is circulating is coming around me
I have fond memories of fireworks when I was a kid and I still enjoy the shows. On a clear 4th of July night with so many people out, it's a good time to introduce his friends and family to heaven. There is often time before the big explosion to watch during the twilight and even later at night after arriving home.
Each panel shows bright planets and stars visible at dusk on July 4th. Look low in the northwest to see Venus and Mercury and south for bright Jupiter and Saturn.
Stellarium
This season there is much to see at dusk, including Venus and Mercury in the western sky and Jupiter and Saturn in the south. The Summer Triangle shines to the east with the flickering Arcturus campfire color in the southwest sky. Show the children how to connect Jupiter, Arcturus and Spica in the giant "Jupiter triangle".
Do not Forget Antares! Located midway between Saturn and Jupiter, this red supergiant star is the summer version of the famous winter giant, Betelgeuse. Both are likely to explode in the form of supernovae in the not-too-distant future, returning freshly-forged elements to the interstellar medium that might be useful for another special occasion in a distant time.
Astrophotographer Damian Peach created this animation using a reference image of Mars Global Surveyor and his own photo of Mars taken on June 28 to show how dust has transformed the appearance of the planet.
NASA / Damian Peach
Once the children are in bed, point a telescope on the next planet in the parade, March. The recent dust storm swallowing the planet continues to transform the appearance of surface features on the red planet. The Sinus Meridiani club, the "eye" of Solis Lacus and even the mighty Syrtis Major have been so modified that they are almost impossible to recognize. Only parts and parts remain visible under expansive clouds of obscuring dust. The debris covers even a large part of the southern polar cap, which will otherwise shine like a snow-white.
The comet 21P / Giacobini-Zinner gets closer and closer! This photo, taken on July 1st, shows a compact coma and a short tail pointing to the southwest. The north is rising. Comet 21P is a small comet with a nucleus 2 km wide
Alfons Diepvens
Passing planets to objects of the deep sky, fans can also watch the comet back 21P / Giacobini-Zinner as he heads north through Cygnus in Cepheus this month. Although still of magnitude 11-11.5, it brightens rapidly and is expected to reach magnitude 7 by the end of August. Am I wrong or is it like we have a binocular comet? I found the little blur on July 2.16 UTC in my 15-inch reflector. With a magnification of 64 ×, I observed a moderately condensed coma of one diameter, with a false star core and a tail of 2 ° pointing to the southwest
Comet 21P / Giacobini-Zinner travels from Cygnus to Cassiopeia this month, illuminating all the time. The stars in this table and in the graph below are shown at magnitude 9.5 with the positions marked at 0 h UT every three days from July 4th. Click to Enlarge and Print
Chris Marriott's SkyMap with Author Additions
Discovered in 1900, the 21P / G-Z became the first comet to be visited by a spacecraft. On September 11, 1985, NASA's International Sun-Earth Explorer 3, renamed International Cometary Explorer (ICE), went straight by its tail and collected data on the interaction of the comet with the solar wind. Perihelion occurs on the 10th of September, one day from its closest approach to the Earth (0.39 to 58.4 million km).
The comet PanSTARRS (C / 2017 S3) accelerates quickly this month by leaving Cassiopeia. in Auriga. It's best seen just before the start of dawn.
Chris Marriott with additions from the author
This is not all news of the comet this month. Comet PanSTARRS (C / 2017 S3) which had chillin 'at magnitude 12.5, experienced an explosion sometime on June 30, reaching a magnitude of ~ 9.5 overnight. Located at Camelopardalis in the northeast of the Double Cluster, it was super evident in the low-power 15 inch July 2, 18 UT, appearing as a dense cotton ball and no tail of about 3 "of diameter. It seemed strangely "gaseous", so I applied the Swan Band filter and the brightness and size of the coma rose, a sure sign of a gas blast of the explosion [19659029] Ka-boom! ” width=”600″ height=”370″ srcset=”https://www.skyandtelescope.com/wp-content/uploads/S3-comet-M-Mattiazo.jpg 792w, https://www.skyandtelescope.com/wp-content/uploads/S3-comet-M-Mattiazo-300×185.jpg 300w, https://www.skyandtelescope.com/wp-content/uploads/S3-comet-M-Mattiazo-768×474.jpg 768w, https://www.skyandtelescope.com/wp-content/uploads/S3-comet-M-Mattiazo-583×360.jpg 583w” sizes=”(max-width: 600px) 100vw, 600px”/>
Comet PanSTARRS (C / 2017 S3) on July 2 showed a bright, greenish coma. Two nights ago, it was three times lower
Michael Mattiazzo
Comet C / 2017 S3 can reach magnitude 3 or 4 because it accelerates the sun in the morning sky en route to a perihelion of August 16 . Keep an eye on the included graph and expect the unexpected. The explosion could continue or even trigger the disintegration of the comet. For more information and an additional map until August 11, click here .
Southern observers can search the comet PanSTARRS (C / 2016 M1) in 4.5 inches and more telescopes as it dives to the south. The stars are shown at magnitude 8.
Chris Marriott's SkyMap with additions by the author
While observers in the southern United States and southern points will not see this comet well PanSTARRS particular because of its Nordic declination, they'll have their own comet PanSTARRS, C / 2016 M1. It is currently at its brightest, a small glowing condensed ball at magnitude 9 in the Ara constellation under Scorpius' tail.
We finish where we started – with an explosion. On June 29, Yukio Sakurai of Japan discovered a new nova, brilliant in Scutum at magnitude 10.3. Although it has risen to 11.0, this "guest star" is easy to find just minutes north-east of the Gamma (γ) Scuti 4.6-magnitude star. You can jump to star since Saturn then use this map of AAVSO to study the nova and estimate its brightness. A 6-inch telescope should suffice
Use this map to help you find Gamma (γ) Scuti then click and download the AAVSO chart at the link above (or click on the map). [19659004] Stellarium
Novae occur in nearby binary stars where one of the members is a white dwarf. The dwarf gaseous siphons of the companion in a whirling disc of accretion and finally on its surface. There it is heated and compressed until it burns in a runaway thermonuclear breath. Novae's explosions can shine with a brightness up to 100,000 times that of the Sun. Enough fireworks for everyone!
