Current Positions of the Planets in the Night Sky:

 The Great North American Eclipse,

April 8th 2024:

Positions of the Planets at Totality

by Martin J. Powell

On April 8th 2024 millions of observers in Mexico, the USA and eastern Canada looked skywards to witness a total solar eclipse. For the USA it was the first total solar eclipse since 2017, for Canada it was the first since 2008 and for Mexico it was the first since 1991. The 'Great North American Eclipse' was visible from five Mexican states, fifteen US states and six Canadian provinces. In the USA, it was estimated that 31 million people lived within the path of totality - more than twice the number who lived inside the path of the 2017 total solar eclipse.

The track of totality began at local sunrise just to the north of the Cook Islands at 0640 CKT (1140 CDT or 1640 UT), crossing the Central American mainland in western Mexico at 1107 MST (1307 CDT or 1807 UT). One hour and 36 minutes later, the track left the eastern coast of Newfoundland and headed out into the Atlantic Ocean, ending at local sunset about 470 miles (750 kms) south-west of the coast of County Cork, Ireland at 1855 UTC-1 (1555 EDT or 1955 UT).

This article will not look into the details of the eclipse itself, however, but will examine the naked-eye planets which one could expect to glimpse in the vicinity of the eclipsed Sun (and a little further afield) within a period of up to 4½ minutes of totality. A total solar eclipse is the only circumstance in which planets positioned on either side of the Sun (morning and evening planets) can be observed from Earth simultaneously.

What Planets were Visible During the Eclipse?

Remarkably, all seven Solar System planets were in the vicinity of the eclipsed Sun on eclipse day, spread across an angular distance of about 68° (refer to this diagram for a rough guide on how angles can be measured in the sky using a hand held at arm's length). A star map showing the planets' positions in relation to the Sun at totality can be seen below. However, only four of the seven planets were visible to the naked-eye during totality - two with ease and two with some difficulty:

Venus, at an apparent magnitude of -3.8, was easily seen against the twilit sky caused by the eclipse totality; it likely became visible within the final minute before totality arrived. Venus was positioned 15° WSW (to the right) of the Sun at the time of the eclipse and was at the end of its 2023-24 morning appearance, which saw the planet as a bright 'Morning Star' before dawn for several months. Venus was positioned in the southern half of the constellation of Pisces, the Fishes, although the constellation itself was unlikely to be seen during the eclipse since none of its stars would have been bright enough to cut through the twilight. Venus is technically visible to the naked-eye in full daylight but the planet must be positioned far from the Sun in the sky and of course, one must know exactly where to look for it!

Jupiter (magnitude -1.9) was positioned 29° to the east (left) of the Sun at eclipse totality; it should also have become visible during the final minute leading up to total eclipse. Jupiter was nearing the end of its 2023-24 apparition and was an evening planet, visible towards the west at dusk. The planet was in south-eastern Aries, the Ram, whose brightest star Hamal ( Ari or Alpha Arietis, mag. +2.0) may also have been glimpsed in the twilight - with difficulty - about 15° to the WNW (right) of the planet.

Saturn (mag. +0.9) was positioned 35° to the WSW (lower right) of the Sun at eclipse totality. Being considerably fainter than both Venus and Jupiter, it was only likely to have been spotted during totality. Saturn was in north-eastern Aquarius (the Water-Carrier) and was only a few weeks into its 2024-25 apparition, which would see it shine at its brightest for the year in September. For observers along the track of totality who were located to the north-east of Québec, Saturn would not have been seen because it was too low down in the sky - or it will have set - by the time the eclipse took place (see the sky diagram for Gander below). The planet Mars was positioned just to the right (west) of Saturn and was shining at about the same brightness.

Mars (mag. +1.1) was positioned 36° to the WSW (lower right) of the Sun and was only 1°.4 to the west (right) of Saturn. Like Saturn, the Red Planet was only likely to have been glimpsed during totality. Mars was very distant from the Earth at this time and so will have been more difficult than normal to spot in the twilight. As with Saturn, observers sited along the track of totality who were located to the north-east of Québec would not have seen Mars because the eclipse took place when the planet was either too low down or had already set (see table below). Mars, which appears pale orange to the naked-eye whenever it is bright, was situated in north-eastern Aquarius and, a few days later, would pass Saturn in the dawn sky (an event called a planetary conjunction). Mars was slowly brightening ahead of its closest approach to the Earth in January 2025.

The three remaining Solar System planets were also technically in the line-up on eclipse day, but they were too faint to see in the twilight:

Mercury (mag. +4.4) was less than 6° to the north-east of the Sun at the time of the eclipse. Mercury had just completed its second evening apparition of 2024 and would reach an orbital position known as inferior conjunction (passing between the Sun and the Earth) on April 11th.

Uranus (mag. +5.8) was in eastern Aries, some 31° to the ENE of the Sun and just over 2° to the ENE of Jupiter. Uranus is just above the naked-eye threshold of visibility under dark skies (ca. mag. +6) so it is technically visible to the naked-eye under such conditions.

Neptune (mag. +7.9) was in south-western Pisces, some 21° to the WSW of the Sun and a little over 6° to the WSW of Venus. Even under dark skies Neptune is not visible to the naked-eye, requiring binoculars or telescopes to be seen.

At the time of the eclipse, the Sun was positioned in central eastern Pisces, between the stars Revati ( Psc or Zeta Piscium, mag. +4.9) and Psc (Epsilon Piscium, mag. +4.2), neither of which would have been visible.

The brightness of an eclipsed sky is dependant on several factors and is difficult to determine in advance, so the magnitude of the faintest planets and stars seen at totality is uncertain. Typically, eclipse observers have seen celestial bodies with the naked-eye down to about magnitude +2, although long-exposure photographs will often detect them at fainter magnitudes.

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Direction & Altitude of the Sun and Planets during the Eclipse

The locations of stars and planets in relation to the eclipsed Sun and the local horizon depended upon where along the track of totality the observer was located. In the tables below, the direction and altitude (angle above the horizon) of the eclipsed Sun and the four naked-eye planets are given for over 50 locations across Mexico, the USA and Canada. Direction is given using conventional compass points; altitude is measured as 0° at the level horizon and 90° directly above the observer's head (a point known in observational astronomy as the zenith). Hence an altitude of 30° is positioned 'one-third of the way up the sky' whilst 45° is positioned 'halfway up the sky' (a demonstration of how direction and altitude are measured is shown in the diagram below).

Sun

How high in the sky was the Sun positioned at totality, and in which direction was it? The further north-east along the track of totality an observer was situated, the lower in the sky and the further to the west along the local horizon the eclipsed Sun would have been. As the Moon's shadow hit the Mexican mainland the locals saw the eclipsed Sun positioned high up in the south-eastern sky, but by the time the shadow left Newfoundland the locals there saw it positioned much lower down in the west-south-western sky.¹

The Sun's highest altitude on eclipse day took place in Durango and Coahuila counties in Mexico, where it reached 70° above the SSE horizon at the time of the eclipse.

At the Mexico-USA border the Sun's altitude fell a little to 68° over the southern horizon. As the eclipsed Sun passed through the fifteen US states its altitude steadily fell away and its direction along the local horizon moved further westwards: it was 63° above the SSW horizon in south-eastern Oklahoma, 55° above the SSW horizon in south-western Indiana, 47° high in the South-west in north-western Pennsylvania and only 35° high in the WSW in north-eastern Maine.

In Canada, the eclipsed Sun similarly fell away in altitude and moved westwards along the local horizon as the path of totality proceeded north-eastwards. The eclipsed Sun was 46° above the south-western horizon in south-eastern Ontario, 40° high in the South-west in southern Québec, 35° high in the WSW in central New Brunswick and only 24° high in the WSW in eastern Newfoundland.

To the south-west of about longitude 98°.5 West (just to the west of Austin, Texas) eclipse totality took place ante-meridian (before the Sun reached due South); to the north-east of this longitude totality took place post-meridian (after the Sun crossed due South).²  In the Northern hemisphere, when the Sun or planets are positioned due South they are at their highest point in the sky for that particular day.

Towns and communities in the vicinity of longitude 98°.6 West (to the west and north-west of Austin) from Indian Creek (Brown County, near the path of totality's northern limit) south-south-eastwards to Spring Branch (Comal County, near the path of totality's southern limit) saw the Sun reach due South at some point during totality. Buffalo (Mills County), Cherokee (San Saba County), Valley Spring (Llano County), Blanco (Blanco County) and Spring Branch (Comal County) all saw the Sun attain due South at mid-eclipse.

1. The western coast of central Mexico and the eastern coast of Newfoundland are separated by 53° in longitude and 25° in latitude, the distance between them being 3,375 statute miles (5,432 kms).

2. Technically, all locations along the path of totality situated to the south-west of about 98°.5 West longitude saw totality take place in the morning, whilst those to the north-east of it saw totality take place in the afternoon. However, local time zones and the change to DST a month earlier meant that, according to the local clock times, most sites to the south-west of the 98°.5 West longitude did not see the event take place in the morning, but in the afternoon.

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Planets

At totality, the four visible naked-eye planets - from Jupiter to Mars - extended across 66° of sky. Their locations in relation to the eclipsed Sun and the local horizon depended upon where the observer was sited along the path of totality (see the sky diagrams below). Some key observational points will now be discussed.

From all locations along the path of totality, Jupiter appeared to the left of the eclipsed Sun whilst Venus, Saturn and Mars appeared to the right of it. At a solar elongation of 39°, Jupiter appeared almost twice as far away from the eclipsed Sun as Venus (Jupiter and Venus were about 44° apart in the sky). To the south-west of southern Oklahoma, Jupiter appeared lower than the eclipsed Sun in the sky (i.e. to the lower left of it); to the north-east of southern Oklahoma Jupiter appeared higher than the eclipsed Sun (to the upper left of it).

From along the length of the eclipse totality track, Venus appeared to the lower right of the eclipsed Sun, by an altitude difference which increased the further north-east along the eclipse track one was situated.

At around longitude 99°.5 West, Jupiter and Venus appeared at about the same altitude (59°). To the south-west of longitude 99°.5 West, Jupiter appeared lower in the sky than Venus whilst to the north-east of 99°.5 West Jupiter appeared higher in the sky than Venus.

From all locations along the path of totality, Saturn and Mars appeared to the lower right of both the eclipsed Sun and Venus. They were within 1° of each other in altitude, Saturn being slightly above the Red Planet.

From locations north-east of Vermont, USA and across to Prince Edward Island, Canada, both Saturn and Mars would have been difficult or impossible to see because of their low altitude and/or bright twilight.

From the northern tip of Nova Scotia through central Newfoundland, along which the path of totality passed, neither Saturn nor Mars were visible because they had set by the time the eclipse took place (see the sky diagram for Gander below).

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Sky Diagrams

The varying direction and altitude of the eclipsed Sun and the four naked-eye planets on April 8th 2024 is demonstrated in the following graphic, which shows how they appeared in the sky from five locations sited along the path of totality: Mazatlán (Sinaloa, Mexico), Austin (Texas, USA), Indianapolis (Indiana, USA), Burlington (Vermont, USA) and Gander (Newfoundland, Canada). Observers sited between any of these five locations can gain a sense of where the eclipsed Sun and planets were positioned in the sky by interpolating between the diagrams, whilst also referring to the directions and altitudes given in the tables below for 7 Mexican locations, 36 USA locations and 11 Canadian locations.

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Direction & Altitude Tables

MEXICO

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USA

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CANADA

Although the excitement and the short duration of a total solar eclipse mean that most observers will understandably spend little or no time searching for planets, the spectacle of witnessing the Sun and its family of planets in Earth's daytime sky is a rare and special experience. If the eclipse duration is more than a few minutes then it may be worthwhile spending 30 seconds or so looking away from the eclipsed Sun and taking in some of the wider aspects of the event:  the colours and brightness of the sky around the eclipse, the colours of the twilight around the horizon, the extent of the darkness across the landscape (and, where possible, its effects on the behaviour of the local wildlife), changes in the air temperature and of course, how many planets and stars can be seen by the naked-eye.

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Future Total Eclipses across North America and Mexico

After 2024 the next opportunity to witness a total solar eclipse over any part of the USA will be on March 30th 2033, when the path of totality will cross western Alaska. Three planets will be potentially observable during that event, spread across 29° of sky.

Canada gets its next opportunity to see another total eclipse on August 23rd 2044, when the path of totality crosses four provinces (the Northern Territories, British Columbia, Alberta and Saskatchewan). In this event up to four planets are potentially visible within 128° of sky. The USA also gets a look-in, the path of totality crossing into Montana, North Dakota and a small part of South Dakota; from all of these locations the eclipse takes place close to sunset. Owing to the low altitude only three planets will be potentially visible from these states, across 85° of sky.

The next total eclipse to extensively cross the contiguous United States will be on August 12th 2045, when the path of totality crosses fifteen states in a clockwise arc from northern California to Florida. On this occasion up to three planets will be potentially visible, spread across 64° of sky.

Finally, Mexico will witness its next total solar eclipse on March 30th 2052, when the path of totality crosses seven states in the central region of the country. It will also touch six southern US states (Texas, Louisiana, Alabama, Florida, Georgia and South Carolina). Up to four planets will be visible on this occasion, spread across 111° of sky.

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Credits

• The star chart was created using by the commercial software MegaStar (by Willmann-Bell, Inc). Star colours were based on those shown in "Patrick Moore's Colour Star Atlas" (Mitchell Beazley Publishers Ltd., London, 1973).

• The directions and altitudes of the eclipsed Sun and the four naked-eye planets were determined using the 'Night Sky Map & Planets Visible' utility at TimeandDate.com.

• The towns, communities and cities shown in the table were selected from information available at GreatAmericanEclipse.com and Astronomy magazine. Other useful sources of information included Eclipse2024.org, TimeandDate.com's interactive map of the April 2024 eclipse and Time magazine's list of future total eclipse maps.
• The map of North & Central America used in the sky diagrams graphic was modified from the image files 'Map of North America including states and provinces' (derived from the file 'Abies bracteata range map.svg' by Halava and authored by Kaldari) and 'Map of Mexico, with states borders' ('Mexico blank.svg' by Yavidaxiu) authored by Sémhur. The source maps can be seen here (North America) and here (Mexico).

Copyright  Martin J Powell  December 2023