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Astronomy
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This website has been created by and is supported by a group of Boston, MA - area amateur astronomers. It is intended to be a convenient site to access news and information about astronomy and space-related activities of interest to the community and the public.













 



 


 

 September Astronomy-Related Events in the Boston Area   

   

  

  

Friday, August 29 - Monday, Sept. 1, 2014

Arunah Hill Days
Cummington, MA
http://www.arunah.org/events/ahd.htm

 

 

Thursday, September  25, Monday, September 29

Acadia Night Sky Festival
Acadia National Park, ME
http://www.acadianightskyfestival.com/

  

 

Friday, September 26 - Saturday, September 27

AstroAssembly
Seagrave Memorial Observatory,
North Scituate, RI
http://www.theskyscrapers.org/astroassembly2013

  

  

Plus:

  

Wednesdays:

Boston University

Boston, MA.
Open Night at Coit Observatory most Wednesdays 8:30 PM - 9:30 PM. 
http://www.bu.edu/astronomy/events/public-open-night-at-the-observatory/

 

  

Fridays:

Guililland Observatory

Museum of Science

Boston, MA

"Astronomy After Hours" Friday nights 8:30 PM - 10:00 PM.

http://www.mos.org/public-events/astronomy-after-hours

 


 

The Sky Report for the Month of September 2014

 

 

 

Current Night Sky: At A Glance

 

Phases of the Moon:

First Quarter

September 2

7:11 AM EDT

Full Moon

September 8

9:38 PM EDT

Last Quarter Moon

September 15

10:05 PM EDT

New Moon

September 24

2:14 AM EDT

 

 

 

The Moon & Planets:

  

The Moon & Planets:

 

In the predawn hours of September 20th, Jupiter rises with the waning crescent Moon to its lower right. In the evening sky on the 27th, a waxing crescent Moon lies to the lower right of Saturn. On the 29th, the lunar crescent lies about 5° above Mars.

 

Evening Planets (after sunset):

  • Mercury, in W
  • Mars, in SW
  • Saturn, in SW
  • Neptune, in SE
  • Uranus, in E

 

Visible At Midnight:

  • Neptune, in S
  • Uranus, in SE

 

Morning Planets (before sunrise):

  • Uranus, in SW
  • Venus, in E
  • Jupiter, in E

 

 

Comets:

 

  • There are no comets visible brighter than magnitude 8.

 

Meteors:

·          There are no significant meteor showers in September.



  •   

A Schedule of Events

 

  • Aug. 1 Fri. (all day)   Lamas - a "cross-quarter" day
    Aug. 3 Sun. 7:00 PM EDT Moon 2.2° NNE of Mars
    Aug. 3 Sun. 8:50 PM EDT First Quarter Moon
    Aug. 4 Mon. 7:00 AM EDT Moon 0.13° WSW of Saturn
    Aug. 8 Fri. 12:00 PM EDT Mercury @ superior conjunction with Sun
    Aug. 10 Sun. 1:48 PM EDT Moon @ perigee (55.96 Earth radii) - nearest of year
    Aug. 10 Sun. 2:09 PM EDT Full Moon ("Full Sturgeon Moon") -  a "Super Moon"!
    Aug. 12 Tue. 8:15 PM EDT Perseid Meteor peak
    Aug. 17 Sun. 8:26 AM EDT Last Quarter Moon
    Aug. 17 Sun. 10:00 AM EDT Autumn Equinox on Mars
    Aug. 18 Mon. 12:00 AM EDT Venus 0.21° N of Jupiter (closest planet conjunction of year)
    Aug. 23 Sat. 10:00 AM EDT Moon 5.3° SSW of Jupiter
    Aug. 23 Sat. 11:00 PM EDT Moon 5.5° SSW of Venus
    Aug. 24 Sun. 2:00 AM EDT Moon @ apogee (63.74 Earth radii)
    Aug. 25 Mon. 10:13 AM EDT New Moon
    Aug. 25 Mon. 2:00 PM EDT Mars 3.4° SSW of Saturn
    Aug. 29 Fri. 10:00 AM EDT Neptune @ opposition
    Aug. 31 Sun. 2:00 PM EDT Moon 0.96° E of Saturn
    Aug. 31 Sun. 5:00 PM EDT Moon, Mars, and Saturn within circle 4.87° in diameter
    Sept. 2 Tue. 7:11 AM EDT First Quarter Moon
    Sept. 8 Mon. 9:38 PM EDT Full Moon
    Sept. 15 Mon. 10:05 PM EDT Last Quarter Moon
    Sept. 24 Wed. 2:14 AM EDT New Moon
  •   

  • Bold Type = Important or Way Cool

  •  

  • * = approximate                          

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  •  

    The Planets

    

   

Mercury has its worst evening apparition of the year for observers in the Northern Hemisphere. It reaches greatest eastern elongation from the Sun - 26° - on September 21st. However, the ecliptic lies at such a shallow angle to the horizon that Mercury is only 7° above the horizon at sunset, and 3° high a half hour later when the sky might be dark enough to spot it. It retains this altitude for several days before and after this date. Mercury is actually quite bright at magnitude 0.0, so it might be easy to spot in binoculars in spite of its low altitude.

 

 

 

Saturn is getting increasingly low in the western sky after sunset. On Sept. 1st, the planet lies 24° above the western horizon a half hour after sunset; by the 30th, its altitude is just 13° 30 minutes after sunset. At midmonth its disk spans 16 arc-seconds, while its rings stretch 37”, and are tilted 22° to our line of sight. This month represents the last opportunities to get good views of Saturn, so take advantage of the opportunity! When will Saturn return? Please check our “What’s New” page to find out!

 

 

 

On September 1st, Mars lies just 5° to the right of Saturn, but the gap widens as Mars moves eastward. On the 27th, Mars passes just 3° to the south of its similarly colored rival, Antares. (The star’s name can be translated as “rival of Ares” – the Greek name for Mars). The view of Mars through a telescope is disappointing, as it is only about 6” across – far too small to reveal any surface detail.

 

 

 

Neptune reached opposition on August 29th, which means it was at its closest, brightest, and largest of this entire year. Throughout September, it remains a prime viewing target. At magnitude 7.8, the planet is well below naked-eye visibility, though it can easily be picked up in binoculars if you know where to look. In a telescope, it shows a tiny blue-grey disk about 2.4” across.

 

 

 

Our Solar System’s other “ice giant”, Uranus, follows Neptune across the night sky. It rises about an hour and a half after Neptune, in the constellation Pisces. It will not reach opposition until early October, but it is already near its peak magnitude of 5.7 (bright enough, incidentally, to be seen with the naked eye under good conditions). In a telescope, it displays a clear greyish-green disk about 3.7” wide.

 

 

 

Jupiter rises two and a half hours before the Sun as September begins, and four and a half hours before sunrise by month’s end. It shines at magnitude –1.8, and is increasingly easy to see as it climbs higher day by day. In a telescope, it displays a disk 33” across, large enough to show detail even when the planet is low. Its four large moons – Io, Europa, Ganymede, and Callisto – are visible even in small telescopes, and you can follow their changing patterns night by night. 

 

 

 

As September begins, Venus rises about an hour and a quarter before the Sun, and lies about 15° to Jupiter’s lower left. Its brightness – magnitude -3.9 – makes it hard to miss even in the morning twilight. As the month goes on, however, it rises later and later; by the 30th, it is virtually lost in the solar glare.

 

 

 

 

Dwarf Planets/Asteroids:

 

At midmonth, the dwarf planet/asteroid 1 Ceres is about 5.5° to the upper right of Saturn at midmonth.

 

Pluto lies due north of the “Teapot” in Sagittarius; It shines no brighter than magnitude 14.1, and represents a difficult target.  

 

      


  •  

    What's New

  •  

  • When Will Saturn Return?

    I have the privilege of working at two major observatories in the Boston area, and I get a variety of questions from the general public as they are looking - or, more commonly, waiting to look! – through a telescope. One of the most common questions is whether there are more planets visible in the summer or winter, or whether they planets we are looking at are visible at the same time every year. The answer is: well, not quite.

    In order to really explain the cycles of the planets, we need to introduce the idea of “syndonic periods”.  A syndonic period is the time it takes a body to return to the same location relative to the Earth and Sun, i.e., the same point in the night sky.

    Let’s consider the case of Mars. Obviously, Earth and Mars both orbit the Sun, in different periods of time. When the Sun, Earth, and Mars are positioned in a line, Mars is considered to be in opposition. When does the next opposition occur? Earth, being the inner of the two planets, moves faster and completes an orbit more quickly – every 12 months. But by the time Earth has returned to the position of the previous opposition, Mars will have moved on some additional distance along its orbit. Earth will have to move for twelve months plus the additional distance Mars has travelled to duplicate the conditions of the opposition.

     

    There is a formula to calculate such “syndonic periods” among the planets.

     

    Earth’s year is, of course, 1 year long. That of Mars is 1.88 years. The formula for calculating the syndonic period is as follows:

     

     1/Psyn = 1/P1 – 1/P2

     

    where P1 is Earth’s period and P2 is that of Mars.

      

    Plugging in the values above, we find the syndonic period of Mars to be about 2.1 years. (This is actually an approximation, since the orbits of Earth and Mars are non-circular and not co-planar.)

     

    An interesting effect is that, the farther the planet is from the Sun, the closer its syndonic period comes to being 1 year – since the planet moves more slowly as its distance from the Sun increases.

    Here is a table of synodic periods in the Solar System, relative to Earth:

     

    Planet

    Sidereal Period (“Year”)

    Syndonic Period

    Mercury

    0.241

    0.317

    Venus

    0.615

    1.599

    Mars

    1.881

    2.135

    Jupiter

    11.86

    1.092

    Saturn

    29.46

    1.035

    Uranus

    84.01

    1.012

    Neptune

    164.8

    1.006

    Pluto

    248.1

    1.004

     

     

     

    From the table we can see that Saturn returns to its same approximate position in our sky after about 1.035 years, or about 12.42 months.

     

    The positions of the planets in our sky, as seen from our observatories, returns to the same place after approximately one syndonic period. So there is the answer to the visitors’ question – albeit a somewhat complicated one!

  •       


   

September 2014 Star Chart

 

September 18, 2014 Star Chart

       9:00 PM EDT

Looking at Zenith, South at Bottom

   

After dark, the sky is bereft of planets visible to the naked eye. Uranus and Neptune are prominently placed, but they require optical aid and star charts to detect – or, better yet, a “go-to” telescope. The “Summer Triangle” – comprised of Vega, Altair, and Deneb – is almost directly overhead. .The Milky Way still streams across the sky from SW to NE across the sky. The chart above shows more stars than are visible from most urban or bright suburban skies; under dark sky sites – increasingly rare in most areas of the Eastern U.S. - many more stars would be visible.  

            


* Text, graphics, and animations by John Sheff. Graphics courtesy of Starry Night Pro Plus 6 / Imaginova Corp. Starry Night images are used with permission from Imaginova Corp.