2019, June 10: Jupiter at Opposition

Jupiter (NASA Photo)

Jupiter reaches opposition on June 10, 2019.  On that evening, and for a few evenings around that date, Jupiter rises in the southeast at sunset. As the sky darkens further, Jupiter appears higher in the sky.

At this time the planet is about 450 million miles away, yet it looks like a bright star.  The planet is to the left of the golden-orange star Antares.

Jupiter’s oppositions occur about every 400 days, about 35 days longer than an Earth year.  The planet is slower moving than Earth. Jupiter revolves around the sun about every 11.8 (earth) years.

Jupiter moves on a longer track and at a slower speed than Earth.

Once Earth moves between Jupiter and the sun, it speeds away and catches up with Jupiter again in about a year and 35 days.

While we remark that Jupiter is at opposition, this description is related to the notion that earth is stationary and immobile.  While it is inaccurate, it relates to the apparent movement of the heavens, in the same way we use “sunrise” and “sunset.”  Both solar events are from Earth’s rotation.

When Jupiter, and other planets outside Earth’s orbit, appears at opposition, it is at its closest point to Earth.  The planet rises at sunset, appears at its highest in the south at midnight, and sets in the western sky at sunrise.

After opposition, Jupiter appears higher in the sky each night at the same time.  In several weeks it appears in the south at sunset.  It disappears into sun’s glare in December.

If you have access to a telescope, Jupiter is a spectacular sight in that telescopic view.  The colors of its cloud bands are revealed and sometimes the Great Red Spot is visible.  The Red Spot is sometimes described as a long-lived storm.  It’s been observed in the clouds for over 400 years!

Jupiter’s four largest moons appear in the telescope as well.  They look like stars.  The moons are lined up in the equatorial plane.  They are visible through a binocular as well, if you can hold the optics steady enough to see them.

Go outside and take a look for Jupiter in the early evening sky!

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