Category Archives: sky

“the actual day of exactly 12 hours of daylight won’t occur until the 26th”

The Sky This Week, 2011 September 20 – 27 — Naval Oceanography Portal

The word "equinox" implies that the length of day and night are equal on the 23rd, but since the Sun isn’t a point source of light and we view it at sunrise and sunset through a refractive atmosphere the actual day of exactly 12 hours of daylight won’t occur until the 26th. From then until March 16 next year the nights will be longer than the days.

The Sky This Week, 2011 September 20 – 27 — Naval Oceanography Portal

The Harvest Moon early 9/12/11 (watch at sunset 9/11, too)

Full Moon occurs on the 12th at 5:27 am Eastern daylight Time. Since this Full Moon falls closest to the autumnal equinox it is almost universally known as the Harvest Moon. This tradition comes down to us from farmers in Medieval Europe, who took advantage of the unusual geometry of the Moon’s orbit and their high northerly latitude to help them bring in their crops for the winter. At this time of the year the Moon’s orbit intersects the eastern horizon at a shallow angle for Northern Hemisphere observers. The farther north you go, the shallower the angle appears. The net effect of this is that over the course of several nights around the time of the Full Moon Luna appears to rise just a few minutes later on consecutive nights. Most of the U.S. the difference is between 25 to 35 minutes later on successive nights, but in northern Europe the difference is only 10 minutes per night. In the Nordic countries above 62 degrees north latitude the Moon actually rises earlier on successive nights around the time of Full Moon. The "extra" light provided by the rising Moon thus allowed farmers to work well past sunset to harvest their fields, thus giving this particular Full Moon its very appropriate name in sky lore.

August 1st is Lammas, one of the traditional “cross-quarter” days of the ancient Celtic calendar.

The Sky This Month, 2011 July 27 – August 23 — Naval Oceanography Portal

August 1st was Lammas, one of the traditional "cross-quarter" days of the ancient Celtic calendar. Traditionally this date marked the middle of the summer season and was the first of several harvest festivals celebrated in medieval northern Europe. Today it is the only cross-quarter day that is not observed in some form in the English-speaking world. Don’t fear that summer is almost gone, though, since the actual mid-point of the season falls one week later on August 7th.

The Sky This Month, 2011 July 27 – August 23 — Naval Oceanography Portal

Dark Sky Finder

Interesting site shows vast areas of light pollution and smaller areas (almost all along the Rockies) of dark. Be sure to zoom in and pan. Main flaw is placemarks can’t be turned off.

Dark Sky Finder

One Giant Leap 42 Years Ago Today

The Sky This Week, 2011 July 19 – 26 — Naval Oceanography Portal

It is hard to believe that July 20th marks the 42nd anniversary of humankind’s first tentative footsteps onto the surface of another world, but it was indeed on this day in 1969 that Neil Armstrong took that "giant leap for mankind". What is even harder to believe is that on the 21st we will retire the last active American passenger-carrying spacecraft as the shuttle Atlantis touches down in Florida for the final time.

The Sky This Week, 2011 July 19 – 26 — Naval Oceanography Portal

On July 12th the far-flung planet Neptune will complete its first full orbit of the Sun since its extraordinary discovery on the night of September 23rd, 1846.

The Sky This Week, 2011 July 5 – 12 — Naval Oceanography Portal

The end of the week marks an interesting historical “anniversary” of sorts.  On July 12th the far-flung planet Neptune will complete its first full orbit of the Sun since its extraordinary discovery on the night of September 23rd, 1846.  On that crisp autumn evening nearly 165 years ago two German astronomers, Johann Galle and Heinrich d’Arrest, pointed the 9-inch refractor at the Berlin Observatory to a patch of sky in the constellation Aquarius where the French mathematician Urbain J.J. Le Verrier predicted that they would find a planet.  Using a newly-compiled but unchecked star atlas the astronomers quickly found a “star” that was not on the map about one degree away from the place where the new planet was predicted to be.  Careful examination showed the “star” to have a tiny pale blue disc, and thus Neptune was revealed.  Le Verrier’s prediction was based on irregular motions of the planet Uranus, and similar reasoning by the English mathematician John Couch Adams led to a similar solution.  Neither Adams nor Le Verrier could muster much interest in the search for the planet in their own countries; Le Verrier’s letter to the director of the Berlin Observatory ultimately led to the find.  While Galle and d’Arrest are given credit for Neptune’s discovery, they were not the first people to see it.  In December of 1612 and January of 1613 none other than the famous Galileo recorded it as a faint background star near Jupiter, but his crude telescope couldn’t show Neptune’s slow movement against the background stars.

The Sky This Week, 2011 July 5 – 12 — Naval Oceanography Portal

Latest Sunset of the Year 6/28

The Sky This Week, 2011 June 7 – 14 — Naval Oceanography Portal

Due to the complex interplay between modern timekeeping and the elliptical nature of Earth’s orbit we’ll experience the year’s earliest sunrise on the 14th. …We won’t experience the latest sunset until the 28th… Sandwiched in between is the solstice itself, and it is on this day that we experience the longest duration of daylight for the year with the Sun above the horizon for 14 hours and 55 minutes. Summer is almost "officially" upon us!

The Sky This Week, 2011 June 7 – 14 — Naval Oceanography Portal

Today is the last day of maximum day length for the year (14h 31m in Albuquerque per www.sunrisesunset.com)

The Sky This Week, 2011 June 7 – 14 — Naval Oceanography Portal

Due to the complex interplay between modern timekeeping and the elliptical nature of Earth’s orbit we’ll experience the year’s earliest sunrise on the 14th. Here in Washington this occurs at 5:42 am EDT. Old Sol will then gradually begin to rise a tad later thereafter, but the time of sunset is still moving slightly later each night. We won’t experience the latest sunset until the 28th, when the Sun will go down at 8:38 pm. Sandwiched in between is the solstice itself, and it is on this day that we experience the longest duration of daylight for the year with the Sun above the horizon for 14 hours and 55 minutes. Summer is almost "officially" upon us!

The Sky This Week, 2011 June 7 – 14 — Naval Oceanography Portal

The maximum day length in Albuquerque is 14h 31m each day 6/16-27 (per www.sunrisesunset.com)

The Sky This Week, 2011 June 7 – 14 — Naval Oceanography Portal

Due to the complex interplay between modern timekeeping and the elliptical nature of Earth’s orbit we’ll experience the year’s earliest sunrise on the 14th. Here in Washington this occurs at 5:42 am EDT. Old Sol will then gradually begin to rise a tad later thereafter, but the time of sunset is still moving slightly later each night. We won’t experience the latest sunset until the 28th, when the Sun will go down at 8:38 pm. Sandwiched in between is the solstice itself, and it is on this day that we experience the longest duration of daylight for the year with the Sun above the horizon for 14 hours and 55 minutes. Summer is almost "officially" upon us!

The Sky This Week, 2011 June 7 – 14 — Naval Oceanography Portal

The Whirlpool Nebula with supernova

The Sky This Week, 2011 June 14 – 21 — Naval Oceanography Portal

Some 27 million years ago a massive star in an outer spiral arm of a galaxy known as Messier 51 reached the end of its life. Within a matter of minutes the star’s core collapsed onto itself, then rebounded in a cataclysmic explosion known as a supernova. The "flash" of visible light from the dying star, billions of times brighter than the star’s normal light output, enabled Earth-based astronomers to detect the event on May 31, 2011. Supernovae are extremely rare events that occur infrequently in most galaxies. No supernova has been observed within our Milky Way galaxy since the one discovered by Johannes Kepler in 1604. While supernovae are discovered almost daily in very remote galaxies, the opportunity to study one in a nearby galaxy such as M51 comes along only a few times in a decade. Messier 51 is a favorite target of astronomers and may be seen with binoculars or small telescopes from dark locations on a Moonless night. It was nicknamed "The Whirlpool Nebula" by William Parsons, Third Earl of Rosse, who first detected the galaxy’s spiral structure with his 72-inch aperture reflecting telescope at Birr Castle in Ireland in 1845.

The Sky This Week, 2011 June 14 – 21 — Naval Oceanography Portal

When we look up, we look back, even millions of years.

June’s Full Moon is variously known as the Rose Moon, Flower Moon, Strawberry Moon, or Honey Moon.

The Sky This Week, 2011 June 7 – 14 — Naval Oceanography Portal

June’s Full Moon [6/15] is variously known as the Rose Moon, Flower Moon, Strawberry Moon, or Honey Moon. Each of these names derive from the characteristic appearance of June’s Full Moon, which occurs as Luna reaches her southernmost declination of the year.

The Sky This Week, 2011 June 7 – 14 — Naval Oceanography Portal

Due to the complex interplay between modern timekeeping and the elliptical nature of Earth’s orbit we’ll experience the year’s earliest sunrise on the 14th. …

The Sky This Week, 2011 June 7 – 14 — Naval Oceanography Portal

Due to the complex interplay between modern timekeeping and the elliptical nature of Earth’s orbit we’ll experience the year’s earliest sunrise on the 14th. …We won’t experience the latest sunset until the 28th… Sandwiched in between is the solstice itself, and it is on this day that we experience the longest duration of daylight for the year with the Sun above the horizon for 14 hours and 55 minutes. Summer is almost "officially" upon us!

The Sky This Week, 2011 June 7 – 14 — Naval Oceanography Portal