Category Archives: Solar System

General Astronomy, Solar System

Planets of the Month: November 2024

By Erich Karkoschka

Mercury is visible during dusk until the 25th around 6 pm, but it is low and difficult to find.

Venus is 20 degrees to the upper left of Mercury, setting around 8 pm. It is finally setting well after the end of twilight so that it becomes very obvious.

Saturn transits 50 degrees high around 8 pm and earlier later this month. Its rings are 5.4 degrees open, quite thin compared to the average view. From now until next spring, the rings will close completely.

Jupiter is rising in Taurus about when Saturn transits. Its magnitude of -2.8 can cause visible shadows on the ground at very dark sites.

Mars is rising around 10 pm, so that all bright planets are visible in the evening sky this month. Its magnitude goes negative, and its size becomes larger than 10 arc-seconds this month. This is the start of the good period to observe Mars with telescopes.

Uranus and Neptune are located between Jupiter and Saturn with Uranus closer to Jupiter and Neptune closer to Saturn. Uranus is just 6 degrees south of the Pleiades.

Minor planet (15) Eunomia of magnitude 8 transits 87 degrees high in Auriga.

The Moon is new twice this month, on the first and the last day of the month. It is first visible on the 3rd near Mercury, then on the next day near Venus. On the 12th, it occults Neptune at 6:40 pm, an event that lasts around 5 seconds compared to milliseconds for occultations of stars. On the night of the 15th-16th, it occults many stars of the Pleiades, although the Full Moon makes them hard to see. On the 27th, it occults Spica for most of North America, although Tucson is a near miss with both extremely close together at 4 am at the eastern horizon.

Comet C/2023 A3 Tsuchinshan-ATLAS moves from Ophiuchus to Aquila as it fades more and more from being visible in binoculars.

32 inch Cassegrain Project, Astronomical Events, General Astronomy, Solar System

Planets of the Month: AUGUST

By Erich Karkoschka

Mercury will start its visibility at dusk, but will never get very obvious. It remains close to the Sun.

Venus is the evening star during dusk. It passes Beta Virginis on the 13th at only 7 arc minutes in distance, similar to the distance between Jupiter and Saturn during the last winter solstice. But the faintness of the star will probably require binoculars to see it.

Saturn comes to opposition on August 2nd, when it rises at sunset. Around that time, its rings are very bright as compared to the planet.

Jupiter also comes to opposition this month on August 22nd. The evening before, the Full Moon will be right next to Jupiter.

On the evening of August 18th, the Moon occults Nunki, the second brightest star of the teapot asterism in Sagittarius. In Nogales, it will last from 7:47 to 8:01 pm, but in Tucson the Moon will not quite make it, although it will get very close to the star. In between there is a grazing occupation which is rare for such a bright star to get so close to us.
August is meteor month. The Perseids will peak on the night of August 11-12 when the Moon is next to Venus which sets early. It cannot be much better than that!! Look toward the east late evening or early morning toward the constellation Perseus.
Astronomical Events, General Astronomy, Solar System

Planets of the Month: JULY

By Erich Karkoschka

Venus is the “Evening Star” during dusk. Seven degrees ahead in the ecliptic is Mars, but 6 magnitudes fainter than Venus. On the 12th, Venus passes Mars only .5 degrees north. On the 20th, Venus passes Regulus at 1 degree distance. Mars follows behind Venus and passes Regulus on the 29th at only .6 degrees distance. Since they set at 8:30 pm, one has to watch this when it is still bright outside. Regulus should be visible. Mars is half magnitude fainter and will come into view then too.

Mars is close to Venus this month.

Saturn rises once it is dark and it stays up all night. Its opposition will be August 1st.

20 degrees east of Mars is Jupiter. Both planets form a large triangle with Fomalhaut well below them. This is best viewed in the morning when they are higher. The shape of this triangle will change as the distance between Jupiter and Saturn decreases over the summer. The right angle at Jupiter will become a larger angle.

Uranus and Neptune are morning planets.

Mercury has a short showing until July 22. It rises at 4 am below Castor and Pollux and does not come up high before twilight gets bright.

The Moon shortly after New Moon might be barely visible on the 10th. The next day, it will be beautifully paired with Venus to its left and Mars very close to Venus. Even on the 12th, the view will be worthwhile.

General Astronomy, Musings, Solar System

Planets of the Month: MAY

by Erich Karksochka

Mercury and Venus are visible low in the west at dusk.  Mercury is almost 10 degrees higher than Venus and easier to see.  After
mid-month. their separation decreases and Venus appears far brighter than Mercury.  Mercury is visible naked eye until the 26th.  
On the 28th, as Mercury is stationary,  Venus passes by
at only half a degree distance.  In a telescope, their two disks
match in size, but Venus is 300 times brighter and 98 %
illuminated, Mercury only
13 % illuminated.
Mars is still an early evening planet, wandering through Gemini.
Jupiter rises before 2 am and comes about 30 degrees high during dawn. It is separated from Saturn by about 18 degrees.
Saturn rises before 2 am and comes about 30 degrees high during dawn. It is separated from Jupiter by about 18 degrees.
Vesta is still 7th magnitude in Leo, an easy object for binoculars.
During the morning of the 26th, the moon has its first total
eclipse in two years.  Totality is only 18 minutes long, just barely
getting fully into the Earth’s umbra, from 4:10 to 4:28, just as
dawn starts.  The setting moon partially eclipsed around
5:25 should be beautiful.
The moon is only a degree from Venus on the evening of the 12th.
Venus is easier to find than the moon since the moon is only 1 %
illuminated, Venus is essentially full.  If it is clear in the west,
the moon will be just barely visible naked eye.  Three days later, the
moon will be almost as close to Mars.

Solar System

Planets of the Month: JANUARY

By Erich Karkoschka

planet-of-the-month-venusVenus. After the start of morning twilight, Venus rises, but does not come up very high before dawn gets too bright. By the end of the month, Venus will appear dim. On the 11th, the think Moon illuminated only 3 percent, will be just 4 degrees from Venus.

planet-of-the-month-jupiterPlanet Parade Evening Sky (Jupiter, Saturn, Mercury, Moon). Jupiter and Saturn will still be closer than 2 degrees from each other until the 8th. The 7th or 8th is the last day Saturn is visible by naked eye. But don’t neglect these planets the following days! On the 9th, Mercury will be only 1.5 degrees from Saturn. To spot
Mercury, you might also need binoculars, but the close trio is easy to find because of bright Jupiter. The planet-of-the-month-saturn

following evening, Mercury will be closer to Jupiter than to Saturn and probably visible by naked eye. After the 10th, you will see Mercury and Jupiter separating very quickly. On the 13th, the Moon will be next to planet-of-the-month-mercuryJupiter and Mercury, but Saturn will be too low to add to the small configuration. Jupiter will eave the scene at the middle of the month, while Mercury will hold out until the end of the month.

 

planet-of-the-month-marsAfter these three planets have set, Mars remains up until after 1 am It moves from Pisces into Aries in an area without bright stars. With Mars transiting 70 degrees high around 7 pm, it is placed conveniently to be viewed in a telescope. It still shows features at 10 arc-seconds diameter, but not like in October when it was twice as large. On the 21st, Mars passes 1.7 degrees planet-of-the-month-uranusnorth of Uranus, a good opportunity to easily find Uranus in binoculars.

 

 

planet-of-the-month-neptune

Neptune is further west and lower. It is also fainter and more difficult to find.

 

 

Vesta, minor planet number 4, is magnitude 7 in Leo and getting ready for naked eye visibility in February and March.

planet-of-the-month-sunriseDuring January, sunset shifts by 26 minutes. It further shifts for the following five months, but the shift each month will be less than in January. On the other hand, sunrise on the 31st will be only 7 minutes earlier than on the 1st, far eclipsed by the 38 minute shift during March.

 

General Astronomy, Solar System

Planets of the Month: NOVEMBER

by Erich Karkoschka

planet-of-the-month-mercuryBrillant Venus outshines all the stars in the morning sky, passing Spica on the 16th.  Far below Venus is Mercury, next to Spica on the 2nd.  By the 10th at greatest elongation, it is as

 

easy to see as it can be seen planet-of-the-month-venusfrom our latitude.  It disappears at the end of the month.

 

planet-of-the-month-moonThe crescent moon stands between Mercury and Venus on the morning of the 13th, near Jupiter and Saturn on the 18th and 19th, and finally just below Mars on the 25th.

 

planet-of-the-month-marsMars is conspicuous since it is bright orange and high in the sky all evening.  It is still 20 arc-sec in diameter so that telescopes show fine detail.  However, it is receeding fast.  By the end of the
month, it is less than half as bright and only 15 arc-sec in diameter. Nevertheless, this is still better than the maximum in some oppositions.

Minor planet Flora No. 8 can be found with binoculars as magnitude 8 in Cetus, well placed in the evening sky.  It is its best showing between 1980 and 2060.

planet-of-the-month-jupiterJupiter and Saturn are well up during the early evening, transiting
just before sunset.  Saturn is 5 degrees east of Jupiter during early
November, closing to 2 degrees by the end.  We are not far from their closest

 

conjunction in centuries, on planet-of-the-month-saturnDecember 21.  On the 2nd, a telescope shows Callisto in transit as a dark spot.  On the 8th, the dark spot is the shadow of Ganymede, and on the 15th after 7pm, it is Ganymede itself.  Finally, on the 19th until 6:40 pm, it is Callisto again.

planet-of-the-month-uranusUranus and Neptune are also well up in the evening.  Neptune transits earlier than Mars.  Uranus transits at midnight in early November since it came into opposition October 31st.

 

planet-of-the-month-neptune

plutoPluto is easy to find on the 14th since it is only 41 arc-min south of Jupiter.  But it still is a challenge to identify it among hundreds
of other stars of similar magnitude, 14 mag.

 

planet-of-the-month-lunar-eclipseOn the morning of the 30th, there will be a penumbral lunar eclipse with a maximum at 2:43 am.  Since 85 % of the moon will be inside the penumbra, it will be noticeable with the northern edge significantly darkened.

 

 

General Astronomy, Solar System

Planets of the Month: SEPTEMBER

by Erich Karkoschka

planet-of-the-month-mercuryDuring early dusk, Mercury can be spotted in the southwest after the 12th, but only if you are experienced in finding it.  On the 21st, Spica is only 1 degree from Mercury, seen in binoculars.

 

planet-of-the-month-venusVenus is brilliant and rises before 3 am so that it is 40 degrees
high by sunrise.  It races through Gemini, Cancer, and Leo, as the winter constellations take the stage nearby.

 

planet-of-the-month-moonFinally, there is a special occultation of Acrab by the moon on
the 21st.  Tucson is located in the middle of the visibility area.
Is it special because Acrab is a bright star, second magnitude and it is a binary separated by 14 arc-seconds.  So in a telescope one can watch the events for both components happening within seconds. Disappearance will be at 6:20 pm local Tucson, which is at sunset, when Acrab is easily visible in a telescope.  Reappearance will be at7:36 pm.

Full Moon: September (1); Last Quarter (10); New (17); and First Quarter (23).

planet-of-the-month-marsMars rises at 9 pm at the beginning of the month but already at
7 pm at the end, when it is even brighter than Jupiter.  It is even
more outstanding considering that no other bright star is anywhere close to Mars.  At mid month it becomes stationary and starts its opposition retrograde motion.  Its diameter increases from 19″ to 22″, perfect for viewing in a telescope.  After October, we will have to wait 15 years before it gets such good again. On the 5th, the moon will pass within half a degrees of Mars around 9pm.

planet-of-the-month-jupiterJupiter and Saturn are well up all evening, still setting aftermidnight.  Saturn is 8 degrees east of Jupiter all month.
They are stationary mid month.  Saturn’s ring is 23 degrees open this month, the last time it is so open that far for the next 10 years. Callisto’s shadow transits over Jupiter’s disk on the 13th after 11pm. Ganymede’s shadow does the same planet-of-the-month-saturnon the 26th from 7:30 to 11pm.

 

 

planet-of-the-month-uranus

planet-of-the-month-neptuneNeptune comes into opposition on the 11th.  So it can be seen all night through binoculars in Aquarius.  Uranus rises further east around 9pm.

Solar System

Planets of the Month: AUGUST

by Erich Karkoschka

planet-of-the-month-mercuryMercury is up at dawn far below Venus, but not much longer.  The last naked-eye visibility ends August 7.

 

planet-of-the-month-venusVenus rises at 2:30 am and is more than 40 degrees up at sunrise.  It is at greatest elongation on the 12th, 46 degrees from the sun.  It still is brighter than average and can be seen after sunrise, especially on the 15th when the lunar crescent is nearby.  Of course, this pairing is best observed before sunrise.

planet-of-the-month-moonThe best night to watch the moon move is August 8/9, right next to Mars.  When they rise, they are 1.6 degrees apart, narrowing to 1.3 degrees later and back up to 1.9 degrees at sunrise. A challenging first moon after New Moon will be visible on the 19th, but visible with naked eye only if it is completely clear, shortly after sunset.

planet-of-the-month-marsMars rises around 10 pm and is 60 degrees up at dawn.  By the end of the month, it is even brighter than Sirius.  In a telescope, its 15-19 arc-sec disk shows detail.  During many years, it does not get that big.

The first minor planet Ceres is in opposition in southern
Aquarius, but with magnitude 8 not as bright as at other oppositions.

planet-of-the-month-jupiterJupiter and Saturn are well up all evening, just a few weeks past opposition.  Saturn trails Jupiter by 8 degrees in their diurnal motion and also their current retrograde motion across Sagittarius. Ganymede will cast a shadow onto Jupiter on the 14th until 11 pm.  On the 21st it will transit
planet-of-the-month-saturn8 – 11 pm and then show its shadow after 11:30. Another transit will start at 11:30 pm on the 28th. The night before one can see Callisto transiting 8:30 – 12:30, which will look like a shadow due to its dark surface.

planet-of-the-month-meteorAugust is the best month for watching meteors.  The Perseids show up during the first three weeks, peaking on the night of 11/12. During dusk, the radiant is just rising, creating few meteors, but they can go for several seconds across the whole sky.  By Dawn, we are heading right into the stream with up to 1 meteor per minute, but they only last less than half a second typically. The moon will rise at midnight on the peak night, so the evening will be dark.

General Astronomy, Solar System

Planets of the Month: JULY

by Erich Karkoschka

planet-of-the-month-mercuryMercury is visible at dawn during the second half of the month
to the left of Orion.  On the 19th, it is to the upper right of
the extremely thin lunar crescent that is about as difficult to
see as Mercury.  The following days Mercury becomes easier to spot.

planet-of-the-month-venusVenus is the morning star, with -4.7 magnitude at its brightest.
In early July it moves through the Hyades and then shines only
1 degree north of Aldebaran on the 11th.  This is the closest
approach of a planet to Aldebaran during this century.
Venus is a nice crescent in a telescope and large binoculars,
especially early in the month.  Venus is so bright that it can
be seen during daytime.  The best opportunity to find it is on
the 17th when it is 4 degrees to the right of the thin lunar
crescent after sunrise.

planet-of-the-month-moonThe moon celebrates our national holiday with a penumbral eclipse.
At 10:30pm, the upper left part of its disk is 1/3 less illuminated
than the rest of the disk.  This is not noticeable since features
on the moon have larger contrasts.  Despite the eclipse, this
Full Moon is brighter than most others.

planet-of-the-month-mars

Mars rises just before midnight and is 60 degrees high up at dawn.
It reaches -1 magnitude and 15 arc-sec diameter, rising toward
its good October opposition.

planet-of-the-month-jupiterJupiter and Saturn come in Opposition in July and are visible
all night.  Their opposition dates (Jupiter on the 14th and
Saturn on the 20th) are only six days apart, which means that
they are only six degrees apart in the sky.  Since their distance
is larger during all other oppositions between 1981 and 2059, it
may be called a once-in-a-lifetime event.  Jupiter is magnitude
-2.8, almost its maximum possible, Saturn 0.1.  In a telescope
planet-of-the-month-saturnthey show their largest disks, Jupiter 48 arc-sec and Saturn
19 arc-sec, although its rings show up 42 arc-sec wide.
Saturn’s rings brighten significantly for several days around
opposition.  This time they brighten up exceptionally because
the opposition is a perfect lineup as the Earth would be visible
transiting the disk of the sun as seen from Saturn, which happens
once every 15 years.
In the night of July 8 after 1am, Callisto and its shadow will
be visible on Jupiter’s disk, and the same happens for Ganymede
after midnight the following night.  You can also catch the end
of a Callisto shadow transit on the 25th before 9:45pm.

planet-of-the-month-uranus

Uranus and Neptune are up before dawn and will soon be back in
the evening sky.

planet-of-the-month-neptune