Monthly Night Sky Report: July 2017

Another warm month has arrived for those of us in the Northern Hemisphere.  For me, June had many clear nights.  Hopefully July will continue this trend so the stargazers among us can enjoy the night sky!

Lets start the month off with our inner most planet, Mercury.  It will be found in the west after the Sun sets but it may be hard to spot for the first few nights of the month while it lies low on the horizon.  Early in the month, your best chance of seeing Mercury will be on higher ground so nothing blocks your horizon.  By the 9th, Mercury will have nearly doubled its altitude in our sky and will be found in the Beehive Star Cluster, which is one of the star clusters that I have been able to view many times.  However, the sky will likely be much to bright to view the pair through a telescope.  Around the 23rd and 24th of the month, Mercury and the Moon will be found in close proximity from our perspective.  The pair will join the bright star, Regulus, part of the constellation Leo the Lion, on these dates.  Mercury will be visible all month.

Venus, the next closest planet to the Sun, and the closest planet to the Earth, will still be found in the morning sky.  It will rise above the eastern horizon around 3 in the morning, so you early risers should be sure to take a look!  It will be VERY hard to miss brilliant Venus.  As the Sun creeps closer to the eastern horizon, Venus will be found near another one of my favorite star clusters, the Pleiades.  If you own a pair of binoculars, be sure to give Venus and the Pleiades your attention.  By the middle of July, Venus will be found by yet another favorite star cluster, the Hyades.  You may even notice the bright star Aldebaran, which appears noticeably more orange than the other stars in the sky.  By the 20th, the Moon will join Venus in the morning sky which always makes a great pair, in my opinion.  

Massive Jupiter will be easily found in our southern sky after sunset.  As I have mentioned several times, if you have a pair of binoculars or a telescope, be sure to give Jupiter a look.  You will be able to see the four Galilean Moons and if using a telescope, you will be able to make out the cloud bands.  Since Jupiter is high in the sky, it's in a great spot for observations.  Jupiter will fall below the western horizon close to 1 in the morning at the beginning of the month and will set earlier each night.  Jupiter will be visible throughout the month.

Since Saturn reached opposition in June, it will now rise in the east a short time before the Sun sets in the west.  If you are able to stay out late, after Jupiter sets, be sure to point your observing device towards Saturn.  The rings make a spectacular view through a telescope of 4 inches or larger.  You will also be able to view Saturn's largest moon, Titan, as well as a few of the larger moons through a 4 inch or larger telescope.  Saturn will also be visible month long.

Uranus will also be visible this month towards the southeast.  If you are under a dark sky, you should be able to see it with the naked eye.  The views will be enhanced through binoculars or a telescope.  It will be found the constellation of Pisces the Fish and will have a distinctive blue-green glow.  

Neptune will rise shortly before midnight as July begins.  You will need a pair of binoculars or a telescope to spot it among the stars of Aquarius.  A dark sky will also help you find our most distant known planet.  It will appear blue-gray in color.

Everyone's favorite dwarf planet, Pluto, will reach opposition this month which will make it brighter in the sky.  You will need at least an 8 inch telescope to spot it however.  It will be found in the constellation of Sagittarius and may require a few nights of observations to recognize this distant world.  If you have the required equipment, sketch the stars in your eyepiece.  Over the course of a few nights, you will notice that one has changed position.  This is Pluto!

July brings the Southern Delta Aquariid Meteor shower.  This shower will peak on the 30th but you can always see the meteors a week before and after the peak date.  These appear to radiate from the constellation of Aquarius in the southern sky.  You may be able to see up to 20 meteors per hour but this rate may go up if you are able to get to a dark sky site.  Stay tuned for one of the better meteor showers of the year next month!!

Comet Johnson (C/2015 V2) will still be visible during the month of July.  It reached it's closest approach to the Sun as well as the Earth during June.  It can be found near the bright star Spica on the 1st and will travel through the constellations of Virgo, Hydra, and Centaurus throughout the month.  Be sure to get out your binoculars to view this comet.  It will appear as a fuzzy ball in your field of view.  The view improves with larger instruments.

Here is your monthly breakdown.

July 03:  Earth at aphelion (farthest point from the Sun) - 94.5 million miles
July 09:  Full Moon
July 10:  Pluto at opposition
July 23:  New Moon
July 30:  Peak of the Southern Delta Aquariid Meteor shower

Many remarkable discoveries and achievements have occurred during the month of July in years past.  I will only mention a few of these and go into a little more detail on the events that I have found the most fascinating in hopes that you will find them interesting as well.

In the year 1054, the supernova that has created the Crab Nebula was seen on July 4th.  This nebula is over 6,500 light years away from the Earth.  This means that the star actually went supernova 6,500 years before it was seen in 1054.  I have yet to view this nebula through my telescope, but the pictures from the Hubble Space Telescope and others are amazing!  I encourage you to find a few and tell me what you think.  For those with a telescope, the Crab Nebula can be found in the constellation of Taurus the Bull.

On July 9, 1979 the spacecraft, Voyager 2, flew past Jupiter.  This spacecraft is now approximately 115 AU from the Sun.  This distance is 115 times the distance the Earth is from the Sun.  Voyager 2 is on the verge of entering interstellar space, the space between the stars.  Voyager 1 entered this area in 2012 and is still sending information back to Earth.  The smartphone that you use today is much more powerful than the technology used to build and operate both of the Voyager spacecraft.

Very recently, the New Horizons spacecraft made its historic flyby of Pluto.  This occurred on July 14, 2015.  We have received very many pictures and data from Pluto, changing our understanding of it dramatically.  For comparison, it took the Voyager spacecraft over 12 years to reach the distance Pluto is from the Sun, which is about 40 AU from the Sun.  It took New Horizons only 9.5 years to reach this distance.  New Horizons mission is not over yet.  It is currently flying to another target in the Kuiper Belt and is expected to reach it sometime in 2019.

Who could forget about the historic moon landings?!  Apollo 11 touched down on the Moon on July 20, 1969.  The crew consisted of Neil Armstrong, Buzz Aldrin, and Michael Collins.  While Neil and Buzz landed on the Moon, Michael stayed in the spacecraft that was used to rendezvous with the lunar module and return the three astronauts safely home.  They splashed down on Earth 4 days later and were welcomed home as heroes.

The space shuttle program came to an end when Atlantis touched down on July 21, 2011.  I made a trip to the Kennedy Space Center a year or so before this time to watch the last mission of the Discovery shuttle, but unfortunately it was pushed back to later date.  I still had a great time at the space center and if given the chance, I would definitely go again.  Atlantis is currently on exhibition at the Kennedy Space Center.  NASA has been relying heavily on Russia and their space program to take astronauts to and from the ISS.

A few final noteworthy happenings from the month of July are the discovery of dwarf planet Eris on the 29th in 2005, the deployment of the Chandra X-ray observatory in orbit around the Earth on the 23rd 1999, and finally the founding of NASA on the 29th in 1958.  Where would we be today without NASA and the technological contributions that they have made?

Now get outside and look up!

Jupiter

It's about time that I talk about more than your monthly night sky report.  I decided this post should be all about Jupiter since it was recently at opposition in May, and is now a perfect target for binoculars and telescopes, or even the naked eye.

Jupiter was first viewed through a telescope by Galileo in 1610.  He saw the four largest moons, Io, Ganymede, Europa, and Callisto (AKA: The Galilean moons) orbiting Jupiter and used this as evidence to prove that the solar system was heliocentric and not geocentric as was the popular belief during this time.  I encourage you to purchase an inexpensive pair of binoculars to view the Galilean moons.  I own a pair of astronomy binoculars which are 25 X 100 and require a tripod to hold them steady.  A smaller pair such as 7 X 50 or even 7 X 35 can reveal the Galilean moons and are much easier to hold steady with nothing more than your hands.  I had a hard time giving up the view through my binoculars to others during my first time looking at Jupiter.  You can obviously use the binoculars for many other things such as bird watching, but I would recommend using them to look at other astronomy related targets such as the Moon and Venus.

For other details of Jupiter, such as the cloud bands, the Great Red Spot, or seeing the moons transit the surface, you will need a telescope.  I have been able to see all of this with my telescope and enjoy the views every time.  The views can be enhanced with color filters and different eyepieces which I am excited to try in the future.

Jupiter is composed mostly of gas but may contain a small core.  The atmospheric pressure of Jupiter is so great that nothing would be able to reach the center before being crushed.  The cloud bands give off different colors due to the elemental composition of each band.  These colors are typically tan-brown to orange-red in color.

The Great Red Spot of Jupiter is a giant storm that is large enough for 2-3 Earth's to fit inside.  The Great Red Spot has been visible since the 1830's.  The existence is still a mystery as well as its slowly shrinking size.  Many other storms have formed on Jupiter and have since died away, so perhaps the Great Red Spot is slowly disappearing as the storm weakens.

Jupiter has many natural satellites such as the Galilean moons and many smaller sized objects.  Each year, the number of known satellites increases as our instrumentation gets better.  Currently there are 69 known satellites orbiting Jupiter.  They range in size with Ganymede being the largest, which is larger than the planet Mercury and some smaller than the size of a city at approximately 3 miles.  A few of these satellites are actually captured asteroids from the asteroid belt.  Astronomers know this because they are orbiting Jupiter in the opposite direction of the other satellites.

Many objects appear to produce light from reflecting the light from the Sun, such as the Moon and Venus.  Certain objects have a higher degree of reflectivity due to their composition.  Venus is covered by a thick cloud layer which reflects nearly all of the light that it receives from the Sun.  This causes Venus to be the third brightest object in the sky with the Sun and the Moon being the only objects that are brighter.  Jupiter was a mystery for many years because it was giving off twice as much energy than it received from the Sun.  I use the word "energy" here because to see this, you need to look at Jupiter in the infrared instead of visible wavelengths.  It was once thought that perhaps Jupiter was completely radioactive.  By doing some calculations, which I did recently in an astrophysics class and will not bore you with, if the entire planet of Jupiter was radioactive, it would still not give off as much energy as it does.

So what is the cause of Jupiter's energy emission?  The current hypothesis is that Jupiter is actually shrinking!  The difference in size would hardly be noticeable to us.  It would have to shrink by only 500 kilometers (approximately 311 miles) every billion years for it to radiate the amount of energy that it does.  Our solar system is estimated to be approximately 4.7 billion years old.  This would mean that over the life of the solar system, Jupiter would have only had to shrink by about 2300 kilometers (1430 miles).  The average person drives ten times this amount in one year!

As mentioned in an earlier post, there is currently a space mission at Jupiter.  The spacecraft, Juno, was launched in 2011 and arrived at Jupiter in 2016.  Juno is studying the composition, gravity field, and magnetic field, among other things, of Jupiter.  You can learn more about this mission and see stunning photos of Jupiter by clicking here.