Sunday, April 22 , 2018, 4:10 am | Fog/Mist 54º


Dennis Mammana: Mooning Around With Jupiter

View Jupiter’s family of moons after dark this week. Click to view larger
View Jupiter’s family of moons after dark this week. ( illustration)

It was little over four centuries ago that the great Italian astronomer Galileo Galilei first aimed his telescope skyward. It’s amazing how many people believe that it was he who invented the telescope, but this was most likely an invention from Holland; in fact, the Dutch were using the device as a military tool decades before Galileo built his own.

Galileo was the first to use a telescope to study the heavens systematically. Over time, his new optical tube revealed to him mountains, valleys and craters on the moon, spots on the sun and the ever-changing phases of Venus. But when he aimed his telescope in the direction of Jupiter, he received the surprise of his life.

Through his eyepiece the planet appeared unlike the stars. It was a small round disk with two bright points of light to its east and one to its west.

The following night, Galileo looked again, and something was different. The three tiny stars were not where they had appeared the night before — they all lay to the planet’s west. If Jupiter had moved past them as it orbited the sun, he reasoned, then it did not behave as astronomers had predicted. He was anxious to see what would happen next.

After a night of clouds he looked again. He saw only two stars, and both were to the planet’s east. Was he going mad? Was Jupiter swinging like a pendulum in front of the distant stars? Or was something else happening?

Night after night he watched the show, never knowing quite what to expect. Then, a few nights later, he no longer saw three stars. Now there were four — one to the planet’s east, the others to its west.

Galileo soon realized that these intriguing lights were not distant stars at all but rather moons that orbited their parent planet.

It was this historic observation that showed once and for all that the Earth could not be center of the universe, as the ancient philosophers and the Catholic Church had long insisted, for here were four bodies orbiting another world!

Wouldn’t it be cool to repeat this historic observation? You can, and there’s no better time than right now, since Jupiter is in a perfect position for viewing and lies as close to Earth as it will get until 2022.

This week, sky watchers can find this brilliant planet midway up in the eastern sky not long after dark.

With even the smallest telescope, one can make out its cloud systems as pastel brown, tan and white bands, as well as its four Galilean moons, Io, Europa, Ganymede and Callisto, circling the planet from night to night.

And from time to time, one or two of its moons will cast their shadows onto the cloud of this magnificent planet and create tiny black dots that drift across its face during the night.

If you don’t have your own telescope, contact your local amateur astronomy club, observatory or science museum to learn when they might be hosting their next star party, so you can peek at this exciting world.

You’ll really be glad you did!

Dennis Mammana is an astronomy writer, author, lecturer and photographer working from under the clear dark skies of the Anza-Borrego Desert in the San Diego County backcountry. Contact him at [email protected] and follow him on Twitter: @dennismammana. Click here to read previous columns. The opinions expressed are his own.

  • Ask
  • Vote
  • Investigate
  • Answer

Noozhawk Asks: What’s Your Question?

Welcome to Noozhawk Asks, a new feature in which you ask the questions, you help decide what Noozhawk investigates, and you work with us to find the answers.

Here’s how it works: You share your questions with us in the nearby box. In some cases, we may work with you to find the answers. In others, we may ask you to vote on your top choices to help us narrow the scope. And we’ll be regularly asking you for your feedback on a specific issue or topic.

We also expect to work together with the reader who asked the winning questions to find the answer together. Noozhawk’s objective is to come at questions from a place of curiosity and openness, and we believe a transparent collaboration is the key to achieve it.

The results of our investigation will be published here in this Noozhawk Asks section. Once or twice a month, we plan to do a review of what was asked and answered.

Thanks for asking!

Click Here to Get Started >

Support Noozhawk Today

You are an important ally in our mission to deliver clear, objective, high-quality professional news reporting for Santa Barbara, Goleta and the rest of Santa Barbara County. Join the Hawks Club today to help keep Noozhawk soaring.

We offer four membership levels: $5 a month, $10 a month, $25 a month or $1 a week. Payments can be made through PayPal below, or click here for information on recurring credit-card payments.

Thank you for your vital support.

Maestro, Mastercard, Visa, American Express, Discover, Debit

Reader Comments

Noozhawk is no longer accepting reader comments on our articles. Click here for the announcement. Readers are instead invited to submit letters to the editor by emailing them to [email protected]. Please provide your full name and community, as well as contact information for verification purposes only.

Daily Noozhawk

Subscribe to Noozhawk's A.M. Report, our free e-Bulletin sent out every day at 4:15 a.m. with Noozhawk's top stories, hand-picked by the editors.

Sign Up Now >