This morning Jupiter, Saturn, and Mars – the Bright Outer Planets – stretch across the southeastern sky. The gap between Saturn and Mars is 17.9°. Mars is 9.4° to the upper right of Jupiter. Jupiter is 8.5° to the upper right of Saturn
In the starfield Jupiter and Mars are in front of the stars of Sagittarius. Jupiter is 3.7° to the lower left of Phi Sagittarii. Mars is 3.8° to the upper right of Nunki and 4.1° to the left of Kaus Borealis.
Mars marches eastward compared to the starry background. It catches and passes Jupiter on March 20 and Saturn, March 31.
In two mornings, March 4, Jupiter is nearly midway between Mars and Saturn as Mars closes the gaps on the planetary pair.
The morning planet parade is taking shape as Saturn becomes visible in the southeast after its solar conjunction. Three bright morning planets are visible in the southeast before sunrise. During the next month, watch Mars approach and pass both planets. Each morning Mars is noticeably closer to Jupiter. Mars passes Jupiter on March 20 and Saturn, March 31. The three planets have not appeared this close in the sky for about 20 years.
On the next clear morning, look to the southeast, bright Jupiter is low in the sky. It is the brightest “star” in that part of the sky – only the sun, moon, and Venus are brighter. Dimmer Mars is to Jupiter’s upper right. As with our photograph, Saturn may be hiding near a neighbor’s house or tree, to the lower left of Jupiter.
In the sky, without a telescope, these worlds appear as bright stars. As they move through their orbits, they seem to move relative to the constellations. Historically, they were called the “wandering stars” — the “planets.” To our ancestors there were seven known wanderers — sun, moon, Mercury, Venus, Mars, Jupiter, and Saturn. They were so important that the days of the week were named for them.
After the invention of the telescope, these “stars” were first seen as separate worlds.
The 2020 Great Conjunction of Jupiter and Saturn is the closest conjunction of these giant planets since the conjunction of them in 1623.
Was this conjunction observed?
The Jupiter – Saturn conjunction of 1623 occurred in the wake of the invention of the telescope, so observing was in its infancy; yet, the sky was full of planetary activity. A partial lunar eclipse (April 15, 1623) was visible throughout the Americas and in Central Europe, where the moon was setting as the eclipse reached its 90% magnitude. Venus passed Jupiter and Saturn in late June and Mercury passed the planetary pair less than two weeks later, when the planets were about 22° east of the sun. With the inner planets in the vicinity of the impending Great Conjunction and Mars reaching opposition (July 4, 1623), surely sky watchers were observing the planets’ locations to test and revise their planetary motion equations.
By the time of the Great Conjunction on July 16, 1623, the planetary pair was less than 13° east of the sun. By Civil Twilight, the pair was near the horizon at mid-latitudes. Without optical help, the conjunction likely went unobserved, even for those with recently minted telescopes. Even then, the observer needed some luck to find the conjunction.
In later years, two British publications stated that the 1623 conjunction was not observed. In 1886, the Monthly Notices of the Royal Astronomical Society state that the February 8, 1683, Jupiter – Saturn conjunction was the first observed “since the invention of the telescope” and that the 1623 passing went unobserved. The same statement was written in the Journal of the British Astronomical Association in 1897. Perhaps the conjunction was observed without optical aid and recorded from more southerly latitudes, when the planets were higher in the sky.
Did the two British publications make the statements out of parochialism, rather than from factual observations made around Europe regarding the first Great Conjunction observed with a telescope, or was this the first time that the conjunction fit into an eyepiece since the telescope’s invention? The February 24, 1643, conjunction was visible in the western sky during mid-twilight as well as the October 16, 1663, conjunction. At the second conjunction the planets were about 10° up in the southwest at one hour after sunset. However, at both conjunctions, the planets were nearly 1° apart. At the 1683 conjunction, the planets were close, about 0.2° apart, twice the separation of the upcoming event. While the two previous conjunctions were visible to the naked eye and individually in a telescopic eyepiece, the 1683 conjunction was the first observed with both planets simultaneously in an eyepiece. With a separation of 0.1°, the 1623 conjunction would have fit into telescopes eyepieces of that generation, but certainly those early telescopes were unwieldy to steer and hold steady, and the telescope operator needed some persistence during the days preceding the conjunction to follow the converging planets into bright twilight while they had sufficient altitude to observe them. So, while the British publications are accurate about viewing the planets simultaneously through a telescope, the two preceding conjunctions were visible to the unaided eye and individually through a telescope, and this does not speak to the issue as whether the 1623 conjunction when unobserved across all of humanity.
In recent times, Great Conjunctions occurred February 18, 1961; followed by a triple conjunction of the two planets in 1980-81; and the last occurred May 30, 2000, although this was difficult to observe.
In a cold, clear sky with a gibbous moon, morning planets Jupiter and Mars shine from the southeastern sky. Jupiter and Saturn are emerging from their recent solar conjunctions and heading for their Great Conjunction later in the year.
This morning, Mars is nearly 18° to the upper right of Jupiter. During the next 5 weeks watch Mars march eastward compared to the starry background and pass Jupiter on March 20 and Saturn, March 31.
Linkto summary about February 2020’s morning planets.
Here’s the detailed note for this morning:
February 14: One hour before sunrise, the moon (20.6 days past New, 66% illuminated), nearly 36° up in the south-southwest is midway from Spica to Zubeneschamali (β Lib, m = 2.6) and about 2° to the left of Kappa Virginis (κ Vir, m = 4.2). Use a binocular to locate the dimmer stars this morning. Jupiter passes Pi Sagittarii (π Sgr, m =2.9), 1.4° to the lower right of the star. Mars is nearly 18° to the upper right of Jupiter, 1.6° to the upper right of 4 Sagittarii (4 Sgr, m = 4.1) – the western gateway to the bright nebulae in Sagittarius. Watch Mars move through this region during the next several mornings. The challenge is to find a reasonable time to view Mars among the nebulae so that it has enough altitude, but when the sky is still dark enough to find the faint clouds. Forty-five minutes before sunrise, Jupiter is over 10° in altitude in the southeastern sky. Saturn is about 10° to Jupiter’s lower left, nearly 6° in altitude.
On March 20, faster moving Mars overtakes and passes bright Jupiter in the morning’s southeastern sky.
One hour before sunrise, Jupiter is over 16° in altitude above the southeast horizon. This morning is the Jupiter – Mars conjunction! Mars is 0.6° to the lower right of Jupiter.
This morning the Saturn – Mars gap is 7.1°; the Jupiter – Saturn gap, 7.0°.
The next Jupiter – Mars conjunction is May 29, 2022 in the morning sky. At that conjunction the sky has 4 bright planets – Venus, Jupiter, Mars, and Saturn – in the southeastern sky. The moon is nearby, a few days before the closest Jupiter – Mars passage.
As Mars closes in on Jupiter for a conjunction on March 20, the moon joins the scene two days before the conjunction. The lunar crescent makes a pretty triangle with Jupiter and Mars. Jupiter is the brighter planet. The trio makes a small triangle, the moon is 2.4° to the lower right of Jupiter and 2.2° to the lower left of Mars.
Look for the planets and the moon one hour before sunrise in the southeast.