Summer Triangle evening transit

Event Date: October 11th
Time: 7:26(.57) PM


Brief

   If you remember when we started seeing the Summer Triangle's stars during late spring evenings, the later Sunsets meant that we had to wait about a minute later on average, to see them.  That, coupled with them rising four minutes earlier each evening, meant that we saw them high in the east after only about a month, depending exactly when we first saw the stars.  Now, since the Sun has been setting at its fastest rate earlier, being shortly after the September equinox, we are still able to see the Triangle at about transit time for several weeks, when the stars come out. 
   Here is the Triangle at transit time.  I included the meridian this time, to further show where the center is vertically.  Remember, if a line is drawn from each star, bisecting each opposite "side", they all meet at a common point within the triangle shape; that is the center.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

We have a good view of the stars all evening long, up to about midnight when Altair and Vega get low.  Deneb takes a little longer than Vega to set, being a little further north.  Even though it is not completely dark yet, the triangle's stars are easily visible during nautical twilight, while bright(est) Vega can even be seen with the eye alone a little earlier, during the end of civil twilight.  Deneb and Altair take a little longer, with the latter a little brighter, being much closer.  Altair is only 17 light years away, while Deneb is estimated to be as many as 3,000 light years away!
Considering that we can see Deneb, that means that it is not only a huge, hot star; it is an extremely luminous one, at approximately 300,000 times that of the Sun.  If Deneb was half the distance it is from us, it would likely exceed all other stars in apparent magnitude-- even Sirius, which is nearly -1.5.  Vega and Altair on the other hand, are much less luminous, at 61 and 12 times that of our Sun respectively.  Therefore, even though Vega is 8 light years further away than Altair, we see it first, as the sky gets dark.

Uranus and Neptune: similar altitude

Event Date: October 10th
Time: 9:41(.34) PM


Brief

    Here is a review of Uranus and Neptune's altitudes, in comparison to each other.  I did this yesterday with Saturn and Mercury, showing them close yet not exactly the same.  This evening, with both Neptune and Uranus both very slow moving planets [against the stars], the same altitude value for them only changes by a slight amount each night.  They are 35º 27' apart, and about 40º 10' in altitude.  Since Uranus' declination is more north than Neptune, by about 13º, its change in altitude is faster than Neptune's; I talked about this with Mercury and the Sun yesterday.
Using the gridlines in the image, see how the two are very close to precisely the same altitude.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   As both planets move in either retrograde or prograde, with Neptune going back to prograde first before the year ends, that means that the time of being the same altitude will not always reflect sidereal time, of 3 minutes, 56 seconds.  We also need to take the changes of declination into account, and Uranus is more affected by this than Neptune.  As mentioned earlier this year, Uranus is closer to the celestial meridian, where declination change is faster than where Neptune is.  The celestial meridian, equator and ecliptic are also included in the image.
   Each night, using an altitude/azimuth telescope, try to find a time-pattern for when at the same altitude.  Using a medium-low magnification to center each planet.  By slewing left or right, if you find both in the middle of the field, they are the same altitude.  Remember when doing this, do not change the telescope itself in altitude when slewing, or it will make it harder to keep both centered.

Saturn and Mercury: similar altitude

Event Date: October 9th
Time: 6:45 PM


Brief

    At the beginning of the month, I showed Saturn and Mercury at the same azimuth.  They are different ecliptic latitudes, and since then, Mercury has moved further from the Sun; it is approaching greatest elongation later this month, while Saturn approaches conjunction.  At magnitude -0.2, Mercury can still be found with the unaided eye, and the Sun's rapid change in setting time has slightly helped keep it at a decent-yet-low- altitude once the sky is dark.
Here are the planets 7.2º apart. 

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   Dimmer Saturn (+0.6) is too dim to be seen with the Sun's glare until the Sun gets low enough.  Even at that point, a horizon with no obstruction will be required to see it.  With atmospheric pollution, optical aid will be required to see Saturn with any ease.  Also, each day, as the Sun moves about a degree east, Saturn only moves a tiny fraction of that, so will fall behind the Sun by month's end; we see it as a morning planet by the end of November, when rising early enough before the Sun to be visible.
   Also, when I last showed the two last time, they were the same azimuth, while this time, they are nearly the same altitude, at 6.3º for Mercury, and 6.5º for Saturn.  Since Mercury is further south, it will set first.  However, Saturn will set lose altitude slightly faster.  At 7:07.17, the altitude of both will be the same for both, at 2º 16.78'. 

Andromeda Galaxy transits high

Event Date: October 8th
Time: 12:43(.02) AM


Brief

   The time of this journal is less than 5 hours after yesterday's.  Then, I showed the galaxy rising, and here, I will show it transiting...looking north!  For lots of our stars and constellations, we face south at transit, even if close to zenith.  However, with a declination of 41.4º, more than 3 degrees better than a declination that puts an object at zenith as seen from our latitude, Andromeda's local path never puts it on the south side of the sky.  When it reaches transit, its azimuth value decreases very fast in value, during the last several seconds.  Before talking about that, let's show it at transit, about 86.4º high.

Detailed

   When a fixed celestial body--whether a star or deep sky--transits with a declination that puts it south of zenith, it picks up movement in azimuth gradually.  However, when having a declination that puts it north of zenith, that means that at some point during its rise, it stops moving north to east, is briefly stationary, and gradually starts moving the other way, from east to north.  While this is gradual at first, it can get fast in a hurry, during the last seconds before transit.  By showing the celestial grid and taking out the alt-az one, we can see how north the galaxy is, with the gridline closest to the galaxy tracing out a parallel local path of it.  Looking at the image, the left and right sides about the same altitudes as Polaris near the center of the inner circle, are approximately where the galaxy stops moving east in azimuth and back towards the north, while rising.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

  

Andromeda Galaxy seen higher in evening

Event Date: October 7th
Time: 8:00 PM


Brief

   I talked about the Andromeda Galaxy (M31) earlier in the year, when it was visible as a morning object.  As the closest bright galaxy to us, we mainly see the core through most telescopes, and to see more than that would require a large enough field of view.  Of course, skies need to be as dark as shown below to see more than the core with the eye alone, with no light pollution.  The galaxy is not too difficult to find if you know which stars to use to "hop" to it from the head of Andromeda.  The first image shows the position of the galaxy in relation of the stick figure of its namesake constellation.  Although no stars are labeled there, they are in the second image, which can be used it find the galaxy.  In that one, zoomed in somewhat, I eliminated the stick figure, to see the separation of the stars more clearly with no lines in the way.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   As shown, Alpheratz is the head star of Andromeda, and we can imagine a line connecting the stars seen to its left when rising: Pi and Mu Andormedae are bright enough to see in somewhat light-polluted skies, although not easy. Nu Andromedae is a little dimmer, while the galaxy's apparent magnitude (4.5) is only a little dimmer than the stars.  Once again, if the sky is dark enough, it is possible to see the more of the 2.1º angular-sized galaxy; over a degree of it, and more if even darker.  As shown in image two, it is enhanced somewhat, and we are seeing it brighter than we will in most skies.  I mainly did this to show how much of the galaxy we see compared to when we try in light pollution.  Even with a telescope of 3 or 4", seeing the core is easy enough in all but perhaps the most Moon-polluted of skies.  The Moon does pass near the galaxy when it passes through Pisces and Aries, and will be in full or gibbous phases for the next few months.

Jupiter and Moon set as a pair

Event Date: October 5th
Time: 7:30 AM


Brief

  Today's time jump is only 9 hours from yesterday's journal entry's, as I now show the Moon and Jupiter paired a little closer than they were at 10:30 last night, on the rise.  As seen here, with the time above being about the latest that we can see Jupiter with the eye alone, the Moon has crept closer, and now a little less than 4º in angular separation from Jupiter.  I kept the orbits in, to show once again, how the node of the two is a little further west.  As a result of the Moon's orbit moving along the ecliptic very slowly, the node with it and Jupiter's orbit (not indicated) also very slowly changes.

Here is the morning viewing of the two.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   One other thing that I will mention about the pair, is that even at this time of morning, they are still high in the sky, not setting until about 12:30.  Therefore, if you have even a small telescope, use this image to find Jupiter even during light hours.  Using the software and time bending to find when the Moon is closest, it can help find Jupiter as well.  If your telescope has a low f-ratio and therefore provides a big field with low eye-pieces, both the Moon and Jupiter can fit into the same field.  This means that Jupiter will only be magnified enough to maybe barely see its Moons during the hours of the morning that it is still dark enough to see them at 5th magnitude.  Either way, the pairing of the two in the daytime is fun to look at.
   As the next two weeks pass, the Moon will separate itself from Jupiter, as it wanes in phase towards new, waxes to full, and meets Jupiter again in about four weeks at nearly 3rd-quarter phase.  Monitor each time, where the Moon passes Jupiter during hours when both are visible.  Are the closest encounters further away, or smaller, using the angle measurements?

Uranus after opposition

Event Date: October 6th
Time: 8:00 PM


Brief

   Uranus is about a week past opposition, meaning that it is slightly higher in the sky each day at Sunset.  With the Sun setting earlier by a little over a minute on average during these few weeks of fall, it means that we are seeing Uranus at the same altitude at slightly more than 4 minutes earlier each evening.  Being slightly east of the celestial meridian (not labeled), Uranus spends a little more than 12 hours above the horizon-- about the same about of time that the Sun does during the last days of March.
   The image shows the planet low in the east-southeast.  The sky isn't completely dark yet, being the last minutes of astronomical twilight.  However, with the Sun on the other side of the sky, there is no glare interfering with Uranus, meaning that it is still an easy target with even bigger telescope.

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   The planet is in retrograde and moving very slightly further west each day as a result, it means that we see it with a new star field each week when viewing at high magnifications.  Although barely visible to the eye alone under the darkest of skies, Uranus is high enough now out of atmospheric pollution to see well at mid-evening hours: between 8:30-10, in particular, getting high and at transit just after midnight as the week progresses.  After being in Cetus for a short while, Uranus is still very close to the border with Pisces, yet now back within the boundaries of the two fish.  When it continues in prograde again in a little over two months, it will still be in Pisces.  After going prograde late in the year and continuing that way for about another 7 months, it will make another quick pass through Cetus' part of the sky.  I will monitor the back and forth as it happens.  It is by far, the most back-and-forth by such a distant planet in a long time.