Mercury is back

On September 14th. Mercury will reach “greatest eastern elongation” meaning Mercury will be best viewed just after sunset all mid-September!

To see Mercury look to the west after sunset the main trick here is you want to look a bit after sunset when it’s dark enough that Mercury is visible but if you wait too long Mercury will set. around 8P has been about perfect for me. Mercury will be fairly low on the western horizon at sunset so it is best seen when you have a clear view of the western horizon, which can be difficult from the front range with the mountains directly west of us. I am seeing it where I am in Boulder even with the mountains towering to the west but you will have a better time the further east you go (or even better from a mountain peak).

Mercury was named after the fastest god Mercury with wings on his shoes because Mercury (the planet) moves really fast! Watch Mercury over the next few days and you will see why. Just over the month of September you can watch Mercury bolt into and out of our evening sky.

This is because Mercury is the innermost planet; it's able to race around the sun once every 88 days. If you missed it this time save the date for October 25th 2021 when you'll be able to see it in the east just before sunrise!

This is a fun age calculator that will tell you your age on other planets: https://www.exploratorium.edu/ronh/age/ you will always find Mercury to be the largest since it’s the quickest to get around the sun!

Because Mercury orbits the sun so close and the earth’s orbit is much further from the sun Mercury never gets more than about 20 degrees from the sun in our sky. Astronomers only really count twilight as being over when the sun is more than 20 degrees below the horizon. Meaning you only really see Mercury during twilight making it one of the hardest planets to spot!

The Main thing to see with Mercury in binoculars/telescopes is its phases. Just like the moon Mercury as phases and they are slightly visible in good binoculars or a telescope. You should beagle to see a little lopsidedness to the dot when looking and if you have a good telescope you might beagle to see what phase it's in.

If you want to see Mercury up close in a big telescope book a tour around September 14th AstroTours.org/booking

Job Posting

Seeking Tour Guides

AstroTours.org is a local astronomy tour business operating out of Boulder Colorado and servicing the surrounding area. AstroTours.org is currently looking for multiple tour guides to help during the busiest summer nights. Tours occur at night starting at sunset and last about 2 hrs. Shifts will be 4 to 6 hours long to give time to prep before, and clean/pack up after the tour.

Must:

Be reliable

Be somewhat familiar with astronomy and using a telescope (training will be provided)

Have a driver's licence, and experience driving in the mountains at night.

Be able to lift 55lbs.

Enjoy communicating complex ideas to people from all over the world.

Definitely highlight if you have any of these skills:

Knowledge of folklore surrounding astronomy such as mythology/astrology/indigenous names of stars/etc...

Safety experience; CPR, First Aid, etc…

Knowledge of Colorado nature/flora/fauna/geology/geography/history

Travel experience

If interested and you meet all of “Musts” please send an email to Luke@AstroTours.org with:

• “Job posting” in the title field of the Email

• CV (or resume),

• Letter/email with:

• Brief bio highlighting your astronomy skills/experience,

• What availability you will have this fall/winter,

• Your favorite deep sky object

• And any questions you might have.

Cheers, Luke

Luke@AstroTours.org

Saturn & Jupiter

Saturn reached 'opposition' (closest it'll be to Earth all year) on Aug 2nd and Jupiter reached opposition Aug 19th meaning now's the best time to see both of them!

Saturn is currently appearing in the southeast next to Jupiter (the brightest 'star' in the southeastern sky after sunset) in our evening sky. Saturn is much dimmer than Jupiter but it is much brighter than the stars that surround it. Saturn makes almost a straight line in the sky with Jupiter currently at sunset.

Location of Jupiter and Saturn

Saturn is a true treat in binoculars or a telescope. When you first see it you might see an oval resembling a batman symbol but once you focus your eyes on it you should see Saturn's rings resolve. Saturn never fails to get an “oh wow!” from anyone looking at it up close, the large planet suspended perfectly in the rings is a magical sight to observe with your own eyes. If you really want to test your eyes and equipment you might see ‘the Cassini Division’ which appears as a dark region that separates the bright ring into 2 rings. The rings are made up of countless water ice particles ranging in size from the smallest speck to the size of a house.

Saturn, like the Earth, has solstices and equinoxes. Saturn takes 30 years to go around the Sun meaning 30 Earth years = 1 Saturn year. We see Saturn's solstices by seeing the rings tip towards us and appear to open up and we see Saturn's equinoxes by observing the rings edge on, where it’s difficult to notice the rings at all. Saturn is currently going into equinox, meaning 2021 will be the best time to view the rings till 2028 when they start to open up again

The brightest ‘star’ appearing in the southeast is actually the planet Jupiter. Jupiter is the largest planet in our solar system at 11.6 times the size of Earth in diameter (86,881 miles), making it 1,322 times the size of Earth in volume. You could fit over a thousand Earths inside Jupiter. Being so massive has made Jupiter a solar system within our solar system, as its extreme gravitational pull captures lots of objects as moons of Jupiter.

Jupiter and 4 moons as seen in a pair of binoculars.

If you look at Jupiter with a decent pair of binoculars you will be able to see 4 of Jupiter's moons: Io, Europa, Ganymede, and Callisto. These are called the Galilean Moons as they were first observed by Galileo in his small telescope. They are very easy to make out even in small telescopes/binoculars. Telling which one is which takes several observations over a longer period of time as they are circling Jupiter and you can only see this movement edge on from Earth. To determine a moon’s true distance from Jupiter you must watch the moons to see when they stop getting further from Jupiter, turn around and get closer.

All of the Galilean Moons are interesting places and studied extensively. Io (the closest) is the most volcanic body in our solar system. Europa is the smoothest body in our solar system; it’s believed to have liquid water and therefore possibly life beneath it’s Ice surface. Ganymede is bigger than the planet Mercury, and Callisto (the furthest out) is the most cratered body in our solar system. With a good pair of binoculars you can also see red stripes contrasted with white stripes; this is Jupiter’s atmosphere. The change in coloration is caused by different compounds in the atmosphere that change color when exposed to the light of the Sun.

With a really good set of binoculars or a decent telescope you can see the red spot which is an acid hurricane more than twice the size of Earth that has been observed since at least 350 years ago. A day on Jupiter lasts about 10 hrs, so over the course of a long winter night you can watch Jupiter do a full rotation by watching the great red spot do a lap around the planet.

If you want an up close view of these planets and more please join me on one of my astronomy programs.