Over the next two evenings the 12-13 day old waxing gibbous Moon will pass by the ‘Red Planet’ Mars coming within about 7-8o on Wednesday October 28th and within about 3-4o on Thursday evening October 29th.
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Thursday October 22nd and Friday October 23rd our Moon will be in conjunction with Jupiter and Saturn. On Thursday the 6.5-day old first quarter Moon will be about 3-4o east from Jupiter. Then, on Friday the 7.5-day old waxing gibbous Moon will be about 11-12o east from Saturn.
Joining the trio across the horizon toward the east are the planets Neptune and Mars, as well as Dwarf Planet Ceres.
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Where were you early in the morning on May 31st 2000? Did you notice two bright star-like objects and a thin waning crescent Moon low over the eastern horizon? As the graphic shows the planets Jupiter and Saturn were paired in a close conjunction. This, however is a special conjunction, one that only occurs about every 20 years between these two planets. This is known as a “Grand Conjunction”.
And the next “Grand Conjunction” is this year, December 21st, where we will see the two planets low over the western horizon at sunset local time. If the weather or other circumstances keep this conjunction out of view just be patient, really patient.
The next “Grand Conjunction” following this year is November 5th 2040.
Start a “Grand Conjunction” Watch
Observe Jupiter and Saturn over the next two months as Jupiter catches up with Saturn. During a conjunction, the objects appear to be close physically, but the objects are just in the same direction in the sky. Lunar conjunctions with planets and some stars close to the ecliptic are relatively common however a conjunction between Jupiter and Saturn, called a ‘Great Conjunction’ only happens approximately every 19.86 years. The two planets follow a repeating pattern of within which constellation the conjunction happens. This year it is within Sagittarius the Archer, in 2041 it will be within Capricornus the Sea-Goat, and then in 2061-62 the Great Conjunction will be within Aries the Ram, which is the start of the repeating pattern.
Animated graphics are set to 10-day intervals starting with October 22nd.
Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.
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Tuesday October 20th the 4-day old waxing crescent Moon crosses the plane of the ecliptic moving south. This is known as the descending node, one of two intersections the Moon’s orbital path (dark green line) has with the ecliptic.
On the date of the descending node the waxing crescent Moon will be over the southwestern horizon at sunset local time. Spread across the horizon from west to east are Jupiter, Saturn, Dwarf Planet Ceres, Neptune, and Mars.
Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.
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Sunday October 18th the position of the planet Saturn with respect to the Earth and the Sun places this ringed planet at what is called eastern quadrature. Saturn is at a 90 degree angle from us as this graphic shows. Think first quarter Moon as that is a fair comparison of the relative positions. At this position Saturn follows the Sun across the sky from east to west as the Earth is rotating, meaning that Saturn rises after the Sun and sets after the Sun.
Where is Saturn now? Saturn is over the southern horizon at sunset and is about 6o east (to the left) from the planet Jupiter. Further east is the Dwarf Planet Ceres, then Neptune, and over the eastern horizon is the still brightly shining Mars.
Learn a little (or a lot) more about Saturn by visiting the Cassini at Saturn mission web site. Click here to go to the Cassini Mission web site.
This is a short 5 minute video I made as part of a live musical performance called “Orbit” that I was part of in May 2011. This is a piece from the much longer tour of the solar system performance and video and shows Saturn and some of its moons as viewed from the Cassini spacecraft that month.
Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.
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Tuesday October 13th Mars will reach a point in its orbit around the Sun where it is at opposition relative to the Earth. At opposition The Earth is between the Sun and Mars, or for that matter, between any of the outer planets and the Sun. At opposition both the Earth and the planet at opposition will have near identical heliocentric longitude. The opposition of Mars sometimes happens around the time that Mars is at its respective perihelion, closest to the Sun. If opposition happens during or near when the Earth is at its respective aphelion, furthest from the Sun, (first few days of July) then Mars will appear larger relative to when these dates are further apart.
Where is Mars Now?
What is opposition?
The outer planets reach opposition when the Earth has moved into a position with the Sun on one side and the outer planet on the other side. Because all planets orbit in the same direction (toward the east), and all follow orbits that are slightly more elliptical than circular, oppositions occur at regular intervals of about 12 months (except for Mars). Mars is considerably closer to Earth and is moving faster than the other outer planets, so it takes approximately 26 months for Earth to catch up with Mars for an opposition.
Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.
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Late Tuesday evening October 6th the 20-day old waning gibbous Moon will be 4-5o from the reddish star Aldebaran in the constellation Taurus the Bull.
Aldebaran with its reddish color is known from mythology as the ‘angry eye‘ of the Bull. Aldebaran is also one of the two end stars in the v-shaped group of stars making up the face of the bull. This group of stars is an open star cluster, the Hyades, and is one two open star clusters easily seen with the unaided eye within the constellation. The tiny dipper-shaped Pleiades is the other open star cluster.
Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.
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Our Moon reaches apogee, (furthest from Earth), for this orbit, on Saturday October 3rd. For this apogee the 16-day old waning gibbous Moon will be at a distance of 31.85 Earth diameters, 252,463 miles (406,300 km) from the Earth.
On the date of the apogee the 16-day old waning gibbous Moon will be about 1-2o to the east from the planet Mars and both very visible through the night hours, and shining brightly over the western horizon at sunrise.
Our Moon and Mars should make for an interesting view with binoculars but considering the difference in apparent brightness (Moon: -12.6 vs Mars: -2.52) the Moon’s reflected sunlight will ‘drown out’ Mars. On the other hand, or direction, Venus is still close to the ‘heart of the Lion’ the star Regulus. Venus is unmistakable with an apparent magnitude -4.07 of compared to the 1.34 apparent magnitude of Regulus.
Does our Moon actually go around the Earth as this graphic shows? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*
*Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)
Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to go to bobs-spaces.
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Friday October 2nd if you are a morning type look toward the eastern horizon before sunrise for the inner planet Venus to be about 1o from the ‘heart’ of Leo the Lion, the star Regulus. Look westward, you can’t miss it, for the the just past full Harvest Moon, the waning gibbous Moon, to be within 9o from the planet Mars as the two prepare to set a couple of hours after sunrise local time.
If you can wait, later that day, watch for the Moon and Mars as they rise together a couple of hours after sunset and are separated by about 1o from one another.
Keep on eye on the outer planets Jupiter and Saturn. Jupiter being closer to the Sun than Saturn orbits more quickly and so it is steadily catching up with Saturn for a very close conjunction toward the end of December.
Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.
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On Thursday October 1st Mercury, the innermost planet, will reach its orbital position known as greatest eastern elongation. At that moment Mercury, the Sun, and the Earth, would be arranged in something close to approximating a right angle as this graphic shows.
From our perspective the orbits of Mercury and Venus appear to move from one side of the Sun to the other – from superior conjunction, behind the Sun, out to the left (east) from the Sun to eastern elongation, then reverse and move westward through (inferior conjunction) between the Earth and the Sun to western elongation. From there the inner planet moves eastward going behind the Sun (superior conjunction) and eventually reappearing on the eastern side of the Sun for an eastern elongation. Repeat over and over – do not stop!
The planet Mercury is currently over the western horizon at sunset local time and will remain visible for most of the month.
Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.
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