Jupiter will on Monday, June 6, overtake Neptune in the carousel around the Sun: an event that comes once in 12.7 years.
See the end note about enlarging illustrations.
This space view, from 15° north of the ecliptic plane, tries to clarify what happens. The paths of Earth, Jupiter, and Neptune are drawn for April, May, and June. The orange line is from the Sun to Jupiter and Neptune at the time of the heliocentric conjunction. The other lines are sightlines from Earth to the two planets at the times of their geocentric conjunction (pink) and heliocentric conjunction (yellow).
(The dashed line is the vernal equinox direction, the baseline for mapping everything celestial. Earth is exaggerated 300 times in size, Jupiter and Neptune 50, the Sun 4.)
Jupiter goes around the Sun in just under 12 years (its sidereal period, or period in relation to the stars, to space in general). But when it comes around to where it last overtook Neptune, the much more distant planet has moved slowly on, so the overtaking occurs about 8.5 months later. The last heliocentric conjunction was 2009 Sep. 19, the next will be 2035 Feb. 18.
The conjunctions as seen from Earth (geocentric conjunctions) are more irregular. This time that conjunction happened back in April, when we were out west of the Sun and so had, as it were, a premature view of the planets’ line-up. Earth’s relatively rapid swings from side to side make the planets appear to go into retrograde motion.
If this happens near the times of the planets’ opposition (Earth passing both of them on the inside), Jupiter appears to overtake Neptune, then fall back past it, then pass it again – a triple conjunction. This happened around the time of the 2009 heliocentric conjunction: geocentric conjunctions on May 2, July 10, and Dec. 21.
This time, the paths of the planets are drawn for the months from May to December. The orange lines are the conjunctions of the two types, helio and geo, in the middle of this compound performance.
In that year 2009, Jupiter was retrograding between June 15 and Oct. 15, Neptune between May 28 and Nov. 4, and their oppositions were on Aug. 14 and 17.
Backyard property
The Redfin real estate company of California offers its clients a copious “Backyard Stargazing Guide for Beginners,” and invited Universal Workshop to contribute a tip. You can see my brief contribution some way down this page, under a subheading “Point your feet south.”
I had suggested using this illustration from To Know the Stars.
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Kevan, I think you’re an extreme outlier minimalist. But to each their own! My daypack is 30 liters. I carry my binoculars in their own case on a shoulder strap, so I can get to them quickly and easily when there’s an interesting bird to look at.
Depends on how far you intend to stray with them.When I do me hikes I generally take a 35 litre backpack and even 42mm would be rather too large when space is at a premium and remember with binoculars it’s 42×2!I have found an Opticron 8×25 monocular ideal but sometimes I just take my 5×10 Zeiss Mini Quick monocular especially if it’s around the full Moon or this time of year when DSO’s are challenging due to light.Although the 5×10 doesn’t let in enough light but I had M13 in it in April and it’s interesting to see what you can see…. about double the naked eye I’d say.
I think that 8×42 binoculars provide the best combination of aperture, magnification, and field of view for handheld binocular skywatching, with a size and weight that I can hold up comfortably for extended periods. 10×50’s are a little too big and heavy for me to hold up for a long time, my arms get tired and the view starts to jiggle. My image-stabilized binoculars are 10×42; the image-stabilization wizardry allows for the higher magnification.
Thanks Guy. Fighting light pollution one light at a time!
I appreciate the monthly solar system diagrams in the Astronomical Calendar. You can see at a glance the difference between the overall heliocentric picture and the geocentric sight lines. Good to keep track.
If they’d asked me, I would have given a link to the International Dark Sky Association Outdoor Lighting Basics web page, and summarized the key points (just enough light when and where needed, fully shielded fixtures with warm spectrum lights) and suggested kindly asking your neighbors to turn off their outdoor lights when they’re not using them.
Another excellent point that the contributors missed. I will draw Redfin’s attention to these comments.
Thank you, Guy – visualizing the motion of planets relative to Sun and a moving Earth are great brain exercises. My Questar dates to 1963, and I am 10 years older – your explanations keep it all fresh and fun.
I’d have thought that under ‘recommended gadgets for stargazing’a good pair of binoculars would come first before a Pentax camera? People usually say 7×50 or 10×50 but these are heavy and take up space.I’m a big fan of small binoculars/monoculars and even one’s like 8×25 will show you loads.All I had in New Zealand was a tiny 5×10 monocular and a 8×25 and I saw tons of stuff.
I thoroughly agree about binoculars. I had no control over what other tips would be given.
Learning THIS STUFF IS NOT EASY