Category Archives: General Astronomy

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

32 inch Cassegrain Project, General Astronomy, Solar System

Planets of the Month: JUNE

by Erich Karkoschka

planet-of-the-month-mercuryMercury is easy to see in the northwest in the evening below Castor and Polux at the beginning of June between 8 and 9 pm. It can be spotted until June 15.

 

planet-of-the-month-venusVenus gets so close to the sun that it occults part of the solar corona on the 3rd, the only time until the 22nd Century. Starting on the 9th, it will be the morning “star”, when it will be only 1% illuminated. A beautiful, large, and thin crescent, visible even in small binoculars. Its illumination increases to 18% by the end of the month when it reaches almost maximum magnitude. A special event will be June 19 when the extremely thin crescent Moon will rise 2 degrees below Venus at 4 am. Venus will be obvious while the Moon will be pale as dawn brightens.

planet-of-the-month-moonA Moon/Venus conjunction will take place the morning of June 19 before dawn. The Moon is full June 5, Last Quarter June 13, New June 21, and First Quarter June 28.

 

planet-of-the-month-marsMars rises later but climbs up higher then Jupiter and Saturn by dawn. Mars is brightening toward its October close opposition. Only Venus and Jupiter are brighter than Mars.

 

planet-of-the-month-jupiterJupiter rises around 10 pm, by 9 pm later in June. Jupiter and Saturn are only 5 degrees apart. Jupiter is three magnitudes brighter than Saturn.

 

planet-of-the-month-saturnSaturn rises around 10 pm, by 9 pm later in June. Jupiter and Saturn are only 5 degrees apart. Saturn is three magnitudes dimmer than Jupiter.

 

planet-of-the-month-uranusUranus rises two hours later than Neptune and is still low when dawn starts.

 

 

planet-of-the-month-neptuneNeptune is 1.6 degrees to the northwest of Mars on the 13th.

 

 

Planet-of-the-Month-Solar-EclipseAsia and Africa will experience a solar eclipse on June 21st. It is an annular eclipse, so not quite total. An annular is when the Moon doesn’t quite cover the Sun and there is a small ring of the Sun around the Moon.

General Astronomy, Solar System

Planets of the Month: MAY

by Erich Karkoschka

planet-of-the-month-mercuryMercury becomes visible below Venus after May 12th. It rapidly moves past venus on the 21st and will be easily observable well into June. May 21st, Venus (-4.4 magnitude) & Mercury (-.6 magnitude) have a conjunction (very close together), visible about 1 hour after sunset. On May 24th a two-day old Moon join the pair.

planet-of-the-month-venusVenus is maximum brightness at the beginning of the month and becomes visible before sunset about 45 degrees high. It can even be seen during the afternoon if you know where to look. For example just before 3 pm, look 86 degrees high, essentially overhead. It reverses its prograde motion on the 13th near Elnath and then moves rapidly toward the Sun until it becomes invisible on the 30th. This month is ideal to watch its large, thin crescent in binoculars. By the end of May, it is only 1 percent illuminated. Venus/Mercury conjunction May 21 (see Mercury).

planet-of-the-month-moonThe Moon passes the morning planets from May 12 to the 14th. It will be most impressive on the 23rd and 24th as a thin crescent during dusk near Mercury and Venus. The Moon is full May 7, Last Quarter May 14, New May 22, and First Quarter May 29.

planet-of-the-month-marsMars brightens to zero magnitude, even brighter than Saturn. It is 15 degrees east of Saturn in early May, rising to 40 degrees by the end of May. Visible in the early morning sky all month.

 

planet-of-the-month-jupiterJupiter rises around midnight, dominating the morning sky. Jupiter & Saturn are close all month. A waning Gibbous Moon joins the pair the morning of May 12th.

 

planet-of-the-month-saturnSaturn follows 5 degrees east of Jupiter all month. This is the closest distance since 2000. They will separate until September and then approach again to .1 degree separation in December. A waning Gibbous Moon joins the pair the morning of May 12th.

planet-of-the-month-cometComet PanSTARRS (C/2017 T2) should peak mid May to maybe magnitude 8 or 9.  It will be within 1/2 degree of the Cigar Galaxy (M82) May 23/24 in the northern sky.

Solar System

Planets of the Month: APRIL

by Erich Karkoschka

planet-of-the-month-venusVenus is 40 degrees high at sunset and close to its brightest possible (Magnitude -4.5). After its passage through the Pleiades on the 3rd and 4th, it moves toward Alnath in Taurus. It is visible late into the evening and sets around 10:30 pm. By the end of the month, it is relatively large (39 arch seconds) and 25 % illuminated.

planet-of-the-month-moonOn April 15, the Last Quarter Moon joins the three morning planets in the predawn sky. On April 26, it is closest to brilliant Venus in the evening sky. First Quarter Moon is April 1 and 30, Full Moon April 7, Last Quarter April 14, and New Moon April 22.

planet-of-the-month-marsMars is the third planet to rise in the morning sky, following very close to Saturn at the beginning of April but sepertated by about 20 degrees by the end of the month. Mars is at Magnitude +1.

planet-of-the-month-jupiterJupiter rises at 2 am, dominating the morning sky at a magnitude of -2.

 

planet-of-the-month-saturnSaturn follows Jupiter and is 5 degrees to the east in the morning sky abut the same brightness as Mars at a magnitude of +1.

General Astronomy, Star Parties

Celebrate the Night Sky

by Jim Knoll
Since we don’t have any star parties to talk about and many are at home doing projects, this might be a good time to evaluate your home outdoor lighting to help preserve the dark skies. As many of you know, the International Dark Sky Association (IDA) is located right here in Tucson. Their website is: https://www.darksky.org and they have lots of resources to help you out. Here are some tips to evaluate your own lighting.
– Install lighting only when and where it’s needed.
– Use energy saving features such as timers, dimmers, and motion sensors on outdoor lights. Timers work great to get your attention when they come on.
– Make sure your lighting is shielded so light shines down, not up and does not trespass on your neighbor.
– Educate your friends and neighbors about the importance of good lighting for our health, economy, and environment.
— Artificial light at night can interfere with ecological interactions like predator-prey relationships, interrupts habitat connectivity, influences species’ ability to detect seasonality, and interferes with the human circadian rhythm.
International Dark Sky week is April 19-26, 2020. Join IDA for daily virtual celebrations at: idsw.darksky.org.
Please share with your family and friends.
Spiral galaxies, M77 (face-on) and NGC 1055. Nasa image
Spiral galaxies, M77 (face-on) and NGC 1055.
Nasa image
General Astronomy, Solar System

Planets of the Month: MARCH

by Erich Karkoschka

planet-of-the-month-mercury  Mercury is just visible at dawn. Its greatest western elongation is the 23rd.

planet-of-the-month-venus  Venus is 45 degrees high at sunset, its best once every eight years. Greatest elongation from the sun is on the 24th, when it is half illuminated. On April 3 it will be inside the Pleiades (M45). At magnitude -4.5, it can be seen during the day if one can find it. The Moon visits Venus on March 26 & 27. Uranus is only 2 degrees from Venus on March 8 (within a binocular view).

planet-of-the-month-moon

Moon. First Quarter: March 2. Full: 9. Last Quarter: 16. New: 24. The Moon will visit Venus March 26 & 27.

 

planet-of-the-month-marsMars.  Rises around 4 am at magnitude +1. Mars rises first early in the month, Jupiter is 5 degrees behind, and Saturn another 8 degrees behind. By the 18th Mars has almost caught up with Jupiter and the Moon is very close to both of them. Between the 20th & 31st, Mars will be between Jupiter and Saturn and within 7 degrees of each other. A Mars/Jupiter conjunction is on the 20th and a Mars/Saturn conjunction is on the 31st. After the 31st, Mars will have passed Saturn and will move on while Jupiter and Saturn stay within 6 degrees of each other.

planet-of-the-month-jupiter  Jupiter.  Rises around 4 am at magnitude -2. See Mars write-up for positioning.

planet-of-the-month-saturn  Saturn.  Rises around 4 am at magnitude +1. See Mars write-up for positioning.

planet-of-the-month-uranus  Uranus.   Only 2 degrees from Venus on the 8th.

planet-of-the-month-neptune  Neptune.  Not visible. Solar Conjunction (in the glare of the Sun) is March 8.

planet-of-the-month-sunrise  The Vernal (Spring) Equinox is March 19 at 9 pm MST. This is when the Sun crosses the celestial equator (an imaginary line in the sky above the Earth’s equator). This happens on March 19, 20, or 21 every year in the Northern Hemisphere.

32 inch Cassegrain Project, Solar System

Planets of the Month: FEBRUARY 2020

by Erich Karkoschka

planet-of-the-month-mercury
Mercury is easily visible in the first half of the month during dust in the west. It disappears after the 18th.

 

planet-of-the-month-venus
Venus is 40 degrees high at sunset and even 44 degrees by the end of the month. This is close to the maximum possible. It sets after 9 pm. The Moon will visit Venus on the 27th, a beautiful sight.

planet-of-the-month-mars
MAIN EVENT. Occultation of Mars by the Moon on the morning of February 18, well visible from Tucson before dawn in the southeast. It starts about an hour after Mars rises and lasts for another hour. Mars disappears behind the bright side of the Moon at 4:38 am and will reappear at 5:40 am along the dark side. The disappearance will be visible in binoculars as Mars slowly becomes invisible planet-of-the-month-moonat the bright limb of the Moon. The reappearance will also take about 20 seconds. Since it occurs at the dark limb, it can be observed with the naked eye.

 

planet-of-the-month-uranus
Uranus is 60 degrees high after dusk, visible in binoculars or a telescope.

 

planet-of-the-month-sunrise
Morning Sky. Mars rises at 4 am. Jupiter follows at 5 am, and Saturn at 6 am. These three planets will get closer to each other as the month progresses.

General Astronomy, Solar System

Planets of the Month: JANUARY, 2020

by Erich Karkoschka

planet-of-the-month-mercury Mercury starts to be visible far below Venus in the West on the 26th. It will be well visible in early February.
planet-of-the-month-venus Venus is extending its visibility in the West from 2 to 3 hours and sets after 9 pm by the end of the month.
planet-of-the-month-moon The thin lunar crescent after New Moon in the West will be near Mercury on the 26th and near Venus on the 27th & 28th.
planet-of-the-month-mars Mars rises at 4 am. On the 18th & 19th, it will be 5 degrees north of Antares. Two red objects near each other.
 planet-of-the-month-jupiter  Jupiter will slowly appear in the morning sky starting the 11th.
 planet-of-the-month-saturn Saturn is not visible. It get occulted by the Sun on the 13th.
 planet-of-the-month-uranus Uranus is 70 degrees high after dusk in the SW.
 planet-of-the-month-neptune Neptune in Aquarius gets visited by Venus on the 27th with a separation of only 10 arc minutes, makiong it possible to fit two planets in the filed of view even at high magnification.
 pluto Minor planet #4, Vesta, is further near Uranus in Cetus and still brighter than 8th magnitude.
Astronomical Events, General Astronomy, Solar System

Planets of the Month: DECEMBER, 2019

by Erich Karkoschka
Planets for December 2019

planet-of-the-month-mercury Mercury will be visible until December 19th, rising just after Mars (15 degrees below) before dawn.
planet-of-the-month-venus Venus is in the evening sky, getting higher and more obvious.
planet-of-the-month-moon New Moon will be at Christmas, last visible in the morning of the 24th and coming back in the evening sky on the 27th below Venus and the 28th right next to Venus, a beautiful pair.
planet-of-the-month-mars Mars rises before dawn in Libra, followed by Mercury 15 degrees below.
 planet-of-the-month-saturn Saturn is to the upper left of Venus in the evening sky until December 10 & 11, when Venus passes two degrees south of Saturn. At that time, Pluto is right next to both planets, but 15 million times fainter than Venus and not an easy target. After Christmas, Saturn will be too close to the Sun to be visible.
 planet-of-the-month-uranus Uranus is well placed in the evening for observers with binoculars or a telescope.
 planet-of-the-month-neptune Neptune is well placed in the evening for observers with binoculars or a telescope.
pluto Pluto is next to Venus & Saturn December 10 & 11 but is 15 million times fianter and not an easy target. The brightest minor planet, Vesta, is not too far from Uranus and only slightly fainter.