Greetings from Robert Ferguson Observatory (RFO) www.rfo.org,
Saturn is at opposition this month so is now at its very best for observing.
Jupiter is not far behind, rising in late evening so a good target after looking
at Saturn on these comfortable summer nights.
There is an interesting daytime lunar occultation of an equal double star on 8/2 that should be easily seen as a double event in scopes, and an evening occultation of a bright star a few days later.
We have a chance to catch the tail end of a double shadow transit of Jupiter on 8/15. With luck we will have more and better double shadow transit observing opportunities in the coming months as Jupiter reaches opposition.
Mars is now getting larger and brighter as it approaches a good opposition, with closest approach coming at the end of November. By late this month it will be becoming a worthwhile telescope target.
Unfortunately, the full moon will obscure the best part of the Perseid Meteor Shower this year, though determined
meteor watchers can try viewing during dark hours well before or after the full
AUGUST ASTRONOMY EVENTS TO WATCH FOR [Note: All times are local Pacific Time and calculated for the RFO site.] * Refer to our website under the Menu option "Events and Info"; Upcoming Observing Highlights" for additional details and astronomy events not included here.
Note that it is possible to subscribe to this calendar through your Google Calendar app or other apps compatible with Google calendars.
Moon - On 8/2 there is a daytime lunar occultation of the bright double star Porrima (see below). First Quarter is on the morning of 8/5. On the evening of 8/6 the moon occults the bright star 19 Scorpii (see below). The "Sturgeon" full moon is on the evening of 8/11. That same evening, this full is moon near Saturn around 9:30pm (which is not surprising given that Saturn is nearly at opposition, the planetary analog of a "full moon"). The moon is very near Jupiter around 3am on 8/15. Last Quarter is on the evening of 8/18. The moon is very near Mars around 3am on 8/19, with the bright orange-red star Aldebaran below this pair (see "Mars," below). Look for a very thin 3.4% crescent moon above Venus in the east around 45 minutes before sunrise (around 5:45am in the RFO region) on 8/25. Venus will be nearer the horizon, below the moon. New Moon is very early on the morning of 8/27. Look for a very thin 3.4% crescent moon 6° high and 14° north of due west 30 minutes after sunset (or around 8:16pm in the RFO region) on 8/28. Finally, the crescent moon is in the west around 8:15pm on 8/29.
Mercury - Mercury has an extremely poor evening apparition this month, reaching a maximum altitude 45 minutes after sunset of a bit less than 3° on 8/16. Greatest elongation east is on 8/27. Basically, it will not be easily observable by most people.
Venus - Venus sinks noticeably lower in the predawn east as the month progresses. It rises just before the start of twilight at the beginning of the month but is rising in nautical twilight by the end of the month, becoming much more difficult to spot. It will very soon vanish from the morning sky.
Mars - First, orange-red Mars is very near cyan blue Uranus around 2am on 8/1. They will be separated by 1.4°. Binoculars will be necessary to spot Uranus in the glare of Mars, which will be a bit more than 100 times brighter than Uranus. In binoculars, Uranus will look like a blue star. Mars moves from Aries to Taurus around 8/8 and rises just after midnight mid-month. It brightens to magnitude -0.1 and reaches a disk size of 9.8" by the end of the month. Being in Taurus means that we can compare the color or Mars with that of the bright orange-red star Aldebaran, with Mars the brighter of the two. Use binoculars to help appreciate the colors. The moon is very near Mars around 3am on 8/19 with Aldebaran below this pair.
Jupiter - Jupiter, retrograde in Cetus, rises around 10pm mid-month. The moon is very near Jupiter around 3am on 8/15. There is a double shadow transit on the evening of 8/15 (see below). Details of Galilean satellite events are on our online calendar. In particular, there are shadow transits on the mornings of 8/2, 8/7, 8/14, 8/15 (double), 8/20, 8/21, 8/23, 8/27 and 8/30 (two), as well as on the evenings of 8/12 and 8/22.
Saturn - Saturn, retrograde in Capricornus, is at opposition on 8/14 so now at its very best for telescope observing. At opposition it will be at magnitude 0.3, have a disk size of 18.8", a ring diameter of 43.7" and a ring tilt of 13°. The full moon is near Saturn on the evening of 8/11.
Uranus - In Aries, Uranus begins retrograde motion on 8/24 and rises just before midnight mid-month. Uranus will be very near Mars around 2am on 8/1 (see "Mars," above).
Neptune - Retrograde, moving from Pisces to Aquarius mid-month, Neptune is nearing opposition so at the start of its telescope spotting season this year. It rises around 9:30pm mid-month.
Occultation of Porrima - IMPORTANT: This is a daytime event so care must be taken to avoid looking at the sun with any sort of scopes or allowing sunlight to enter any scopes. The moon will be well separated from the sun in the sky so this can be easily accomplished. The best practice is to position the scope in a location well shaded from the sun but from which the moon is easily viewed.
Magnitude 2.8 Porrima in Virgo is a close equal double star. This should easily be observable as a two-step event in any good scope, especially if at least moderate magnification is used. The reappearance event requires larger aperture scopes for detection and tracking from the disappearance is the best way to accomplish this.
The details below are calculated for the RFO site using Occult4 so the timings will differ as distance from RFO increases and are not of use for those far from RFO. At about 3:16pm on 8/2 the star will disappear behind the moon's dark limb 80° from the north cusp. Then, at about 4:27pm it will reappear from behind the bright limb (about 44° from the north cusp).
Occultation of 19 Scorpii - At about 10:56pm on the evening of 8/6 the magnitude 4.6 star 19 Sco will disappear behind the moon's dark limb about 68° from the south cusp. (Calculated using Occult4 for the RFO site. Details will differ as distance from RFO increases and no occultation may occur for those far from RFO.)
Double Shadow Transit - On the evening of 8/15 there is a double shadow transit of Jupiter by Io and Ganymede's shadows as well as transits by the two moons themselves. In the RFO region, Jupiter rises just before 10pm with Io's transit and the double shadow transit in progress. You will need a low eastern horizon and get Jupiter into telescope view as soon as you can in order to catch the last part of the double shadow transit. By 10:30pm, Jupiter will be about 6° high with Io's transit at 50%. Then, the sequence of events is:
10:38pm Io's shadow transit ends - End of Double Shadow Transit
11:35pm Io's transit ends
11:58pm Ganymede's shadow transit ends
01:09am Ganymede's transit begins
02:30am Ganymede's transit at about 50%
03:40am Ganymede's transit ends
Perseid Meteor Shower - Unfortunately, the full moon interferes very badly with the Perseid meteors this year. Nevertheless we are providing this information since this is such a popular and well-known meteor shower. The peak is predicted for around 6pm on 8/12. This means that the best options for peak observing are between about 9:45pm and 4:45am on the nights of 8/11-12 and 8/12-13. The full moon will be well to the south in the sky so the best bet is to look in the northern sky, which will be the least affected by the moonlight glare.
Also, the Perseids remain active for at least a couple of weeks, though at lower rates, so it is worthwhile looking in a.m. hours in the first few days of the month or in p.m. hours in the week or so after the full moon, when the moon will not be in the night sky.
TIME SEQUENCE SUMMARY OF EVENTS:
ALL CAPS items refer to the sections above.
8/01 - MARS very near URANUS
8/02 - OCCULTATION OF PORRIMA
8/05 - First Quarter MOON
8/06 - OCCULTATION OF 19 SCORPII
8/11 - "Sturgeon" Full MOON
8/11 - MOON near SATURN
8/12 - PERSEID METEOR SHOWER peaks
8/14 - SATURN at opposition
8/15 - MOON very near JUPITER
8/15 - DOUBLE SHADOW TRANSIT of JUPITER
8/18 - Last Quarter MOON
8/19 - MOON very near MARS and near Aldebaran
8/24 - URANUS begins retrograde motion
8/25 - 3.4% Crescent MOON near VENUS
8/27 - New MOON
8/28 - 3.4% Crescent MOON in the west
8/29 - Crescent MOON in the west