Aug 04, 2018: Open House -- More Planets!

Michael Richmond
Aug 04, 2018

It was a nice night to see planets! Some 70 to 80 visitors came to look at Jupiter, Saturn, Mars, and M13 through our telescopes. The International Space Station was a big hit, too, as it lit up the sky for several minutes between 10:15 and 10:20 PM.

Special thanks to our wonderful volunteers:

• Tracy Davis
• Roger Easton
• Jen Connelly
• Christina Magagnoli
• Jessica Chellino
• Amber Dubill
• Evan Putnam
• Will Wainwright
• Ekta Shah

Some handy guides for this evening's skygazing follow.

What will you see in the sky at around 9:30 PM?

• Venus setting on the western horizon
• Jupiter to the southwest
• Saturn to the southeast
• Mars rising in the east

Also available in reverse-color version.

We probably won't see much surface detail on Mars, but here are a few useful facts about the current close approach:

• tonight, Mars and the Earth are separated by 0.387 AU = 58 million km = 36 million miles. That's much closer than the "typical" distance of about 0.52 AU = 78 million km when Earth passes Mars in its orbit.
• because it's so close, Mars appears larger than normal: tonight, its angular diameter is 24 arcseconds, just about half the apparent angular size of Jupiter.
• Mars is also much brighter than usual: tonight, it has magnitude -2.7, which makes it the second brightest object in the sky, after Venus (mag -4.2). It is considerably brighter than Jupiter (mag -2.1).

All four of Jupiter's large moons will be visible tonight:

Also in a reverse-color version

We might see three or four of Saturn's satellites; Titan is by far the brightest.

Also in a reverse-color version

We can also watch out for two bright (and one faint) artificial satellites circling the Earth. First, we'll see a brief, 10-second flash of light as sunlight bounces off the shiny metal antenna of an Iridium communications satellite and down to the Rochester area, at 9:14 PM. Look just east of the bright star Vega.

Image created by Tracy Davis using the Heavens Above site

Just two minutes later, at 9:16 PM, the satellite Cosmos 1633 will fly overhead, also passing close to the bright star Vega.

Image created by Tracy Davis using the Heavens Above site

Finally, about one hour later, at 10:14 PM, the International Space Station will slowly coast across the sky from north-west to south-east, disappearing into the Earth's shadow just before it reaches Aquila the Eagle.

Image created by Tracy Davis using the Heavens Above site

I made a little questionnaire for visitors; perhaps some will be inspired to answer the questions.

Last modified 8/05/2018 by MWR.