Peyton Hall Observatory holds public starwatches led by students of Princeton University's Department of Astrophysical Sciences and are usually at 8 p.m. (9 p.m. DST) on the second Tuesday of each month, but rescheduled for the next week if the skies are cloudy.
Local Moonrise, Moonset and Astronomical Twilight times for the Peyton Hall Observatory are featured in the Eye on the Sky® Almanac.
Detailed Weather Information Sources (including forecasts and current conditions) for the Princeton area can be found on the Eye on the Sky® Weather Page.
Daily Celestial Calendar is calculated by CalSKY.
Interesting Sky Sights and planetary positions for the week are in Sky at a Glance.
A Customizable Map of the sky seen from Peyton Hall Observatory can be found at Your Sky Sky Map.
Which Satellites are Visible from the Peyton Hall Observatory tonight? Heavens-Above will calculate the visibility of all bright satellites (including space shuttles and the International Space Station) brighter than 4.5 magnitude and of sighting opportunities for Iridium flares.
Aurora Borealis can be seen from our area (if the sky is clear and dark) an average of 60-130 days every 11-year solar cycle, especially if the Kp Index is 8 or greater and the Auroral Activity Index is 10 or greater (according to Aurora Chasers, the minimum Kp Index for an aurora to be seen at least 20 degrees above the northern horizon at local midnight is 7.4). The current solar cycle is expected to peak in May, 2013. Middle-latitude auroral activity warnings and watches are available from Solar Terrestrial Dispatch, and the Geophysical Institute of University of Alaska Fairbanks has a current auroral forecast map for North America.
If You're Using Computer Software to plan your skywatch, it may be helpful to know that the location of the Peyton Hall Observatory is 40° 20' 48" north latitude (+40.3466°), 74° 39' 05" west longitude (-74.6516°) in the Eastern Time zone, and altitude is 140 feet (43 meters).

National Weather Service hourly forecast, including percent sky cover every three hours.
Environment Canada's Astronomy Weather Forecasts (forecasts for North American cloud cover, seeing, sky transparency and weather near the ground). The 48-hour cloud cover forecasts start at 10 a.m. and 10 p.m. EST (11 a.m EDT) and are updated from one to two hours afterward.| Last Visibility | New Moon | First Visibility | First Quarter | Full Moon | Last Quarter |
|---|---|---|---|---|---|
| January 2 | January 4 | January 5 | January 12 | January 19 | January 26 |
| February 1 | February 2 | February 4 | February 11 | February 18 | February 24 |
| March 3 | March 4 | March 5 | March 12 | March 19 | March 26 |
| April 2 | April 3 | April 4 | April 11 | April 17 | April 24 |
| May 1 | May 3 | May 4 | May 10 | May 17 | May 24 |
| May 31 | June 1 | June 2 | June 8 | June 15 | June 23 |
| June 29 | July 1 | July 2 | July 8 | July 15 | July 22 |
| July 29 | July 30 | August 1 | August 6 | August 13 | August 21 |
| August 27 | August 28 | August 30 | September 4 | September 12 | September 20 |
| September 26 | September 27 | September 29 | October 3 | October 11 | October 19 |
| October 25 | October 26 | October 28 | November 2 | November 10 | November 18 |
| November 23 | November 25 | November 26 | December 2 | December 10 | December 17 |
| December 23 | December 24 | December 26 | 1/1/12 | 1/9/12 | 1/16/12 |
| Last Visibility | New Moon | First Visibility | First Quarter | Full Moon | Last Quarter |
| Event | Time (EST) |
|---|---|
| Penumbral eclipse begins | 6:31 a.m. |
| Moonset | 7:08 a.m. |
No Twilight or Nighttime Occultations of a bright planet or first-magnitude star by the moon are visible from the Peyton Hall Observatory this year.
Major Meteor Showers peak at the following times, according to International Meteor Organization (IMO). Neil Bone of the British Astronomical Association estimates that under perfect conditions an average of about 3-8 sporatic meteors per hour are visible to the naked eye. Bone says the best place to look for meteors from a specific meteor shower is about 50° above the horizon and 40° to either side of the radiant.
| Shower | Peak Date | Peak Time | Radiant Alt/Az | Lunar Phase (percent illuminated)/ Elongation from Radiant | Meteors per Hour* |
|---|---|---|---|---|---|
| Quadrantids | Jan. 3 | 7:50 a.m. | 1°/NNW | waxing crescent (40%) / 97° | 0 |
| Eta-Aquarids** | May 5 | 7 p.m. | 46°/SSE | waxing gibbous (90%) / 120° | 6 |
| Perseids | Aug. 12 | 1:30-4 p.m. | 34°/N | waning gibbous (62%) / 44° | 9 |
| Orionids** | Oct. 21 | 5 a.m. | -33°/N | waxing crescent (11%) / 96° | 0 |
| Leonids | Nov. 17 | 4:43 p.m. | 34°/WNW | young crescent (1%) / 36° | 10 |
| Geminids | Dec. 14 | 12:10 a.m. | 34°/WNW | old crescent (5%) / 36° | 10 |
* at local peak time(s), calculated by reducing zenithal hourly rate (ZHR) to a limiting magnitude of 4.5 and factoring in the distance of the radiant from the zenith (but does not include the effects of moonlight, sunlight or time of day), based on the International Meteor Organization's 2011 Meteor Shower Calender.
** Eta-Aquarids and Orionids are listed because they are associated with Halley's Comet (Comet 1P/Halley).
The best conditions for watching a meteor shower occur when the radiant at the shower's peak appears high in a dark sky between local midnight and the beginning of astronomical twilight.
| Shower | Peak Time | Local Midnight | Astronomical Twilight Begins | Moon Rise/Set | Moon Above Horizon At Dawn? | Meteors per Hour* |
|---|---|---|---|---|---|---|
| Quadrantids | Fri Jan 3 7 p.m. | 12:03 a.m. | 1/4 5:44 a.m. | Set 1/3 5:33 p.m. Rise 1/4 9:06 a.m. | No | 0 |
| Perseids | Wed Aug 13 12:40 a.m. | 1:04 a.m. | 4:25 a.m. | Rise 8/12 8:48 p.m. Set 8/13 7:23 a.m. | Yes | 9 |
| Geminids | Sun Dec 14 6:40 a.m. | 11:53 p.m. | 5:35 a.m. | Rise 12/13 8:55 p.m. Set 12/14 11:34 a.m. | Yes | 10 |
Space Shuttles launched toward the International Space Station (an inclination of 51.6°) during twilight (when the sun is between 3 and 18 degrees below the horizon) can sometimes be seen from Princeton during the last minute or so before Main Engine Cut-Off (MECO, which occurs about eight-and-a-half minutes into the mission). The Kennedy Space Center provides a schedule and countdown timer for all shuttle launches, which are usually carried live by local radio stations KYW-AM (1060 kHz, Philadelphia) and WINS-AM (1010 kHz, New York City). Our thanks to former NASA Flight Dynamics Officer Daniel R. Adamo for "guidance" and use of his MacMission Control software for the following calculations of the nighttime visibility of an average flight of a shuttle to the ISS as seen from Princeton.
| Mission Elapsed Time (mm:ss) | Altitude | Azimuth | Distance to Shuttle in Statute Miles (Range) |
|---|---|---|---|
| 06:45 | 5° | South | 478 |
| 07:00 | 6° | South | 448 |
| 07:15 | 6° | South | 418 |
| 07:30 | 7° | SSE | 391 |
| 07:45 | 8° | SSE | 367 |
| 08:00 | 8° | SSE | 350 |
| 08:15 | 9° | SE | 298 |
| 08:30 | 8° | ESE | 302 |
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