Category Archives: sky

Moon Phases 2015, Northern Hemisphere

The first link is to a video of all of the phases of the moon in 2015. The second is the first tool I’ve seen that actually displays the moon phase for a given date and time. Pretty cool.

Moon Phases 2015, Northern Hemisphere | Flickr – Photo Sharing!

Moon Phases 2015, Northern Hemisphere

This visualization shows the Moon’s phase and libration at hourly intervals throughout 2015, as viewed from the northern hemisphere. Each frame represents one hour.

Moon Phases 2015, Northern Hemisphere | Flickr – Photo Sharing!

SVS: Moon Phase and Libration, 2015 (id 4236)

The animation archived on this page shows the geocentric phase, libration, position angle of the axis, and apparent diameter of the Moon throughout the year 2015, at hourly intervals.

SVS: Moon Phase and Libration, 2015 (id 4236)

Happy Solstice, Everyone!

Stand still!

The Sky This Week, 2014 December 16 – 23 — Naval Oceanography Portal

The Winter Solstice occurs on the 21st at 6:03 pm EDT, marking the beginning of the astronomical season of winter.  At this time the Sun will reach its most southerly point along the ecliptic at a point above the Tropic of Capricorn some 5000 kilometers (3000 miles) south of the Hawai’ian Islands.  For those of us in the Northern Hemisphere this will also correspond to the shortest length of daylight we’ll experience for the year.  Here in Washington we’ll have just 9 hours 26 minutes between sunrise and sunset.  Of course, for our friends in the Southern Hemisphere, this marks the beginning of summer, and they see their shortest nights.

The December solstice has been an important yearly event that has been observed and commemorated by people since very ancient times.  In particular it was widely observed by the Neolithic people of Europe, and many of the ancient monuments that dot the landscapes of the British Isles and northern France were used to observe the passing of this special day.  Our modern holidays have been adapted from many of these ancient observances, many with a common theme of light to chase away the long winter darkness.  For ancient people this was a welcome turning point in the year since it portended the gradual return of the warming Sun and the (eventual) end of winter.

The Sky This Week, 2014 December 16 – 23 — Naval Oceanography Portal

Long Night Full Moon 12/6 – and the earliest sunsets of the year

Watch the moon rise at sunset on 12/5-7.

The Sky This Week, 2014 December 2 – 9 — Naval Oceanography Portal

The Moon passes through the bright stars of the Great Winter Circle this week, a fitting backdrop for the most northerly Full Moon of the year, which occurs on 6th at 7:27 am Eastern Standard Time.  December’s Full Moon is popularly known as the Moon Before Yule, Cold Moon, or Long Night Moon.  The latter is particularly appropriate as we approach the year’s longest nights around the time of the Winter Solstice.  Watch Luna glide just a degree north of the bright star Aldebaran on the night of December 5th.  On the following night her bright crisp disc hovers above the figure of Orion, the Hunter.  

For most folks living in the mainland United States this week begins the series of phenomena associated with the winter solstice.  For the next 10 days we will experience the earliest sunsets of the year.  Here in Washington they occur at 4:46 pm EST.  By the 12th the sunset time slowly begins to creep a bit later; however, the time of latest sunrise is still advancing.  That event falls on the several days before and after January 4th.  Thus, when we measure the total length of daylight/night, we find that the year’s shortest day indeed does fall on the solstice on December 21st.  This “lag” in the times of sunrise and sunset is a result of our method of keeping time by using a standard second and by the slightly elliptical orbit of the Earth around the Sun.  If we still used sundials for keeping time the effect wouldn’t exist.

The Sky This Week, 2014 December 2 – 9 — Naval Oceanography Portal

2014 Orionid Meteor Shower – NASA Science

 

splash

Orionid meteors fly out of a radiant near the shoulder of Orion, the Hunter.  In this sky map, the radiant is denoted by a red dot. Although the meteors emerge from a single point, they can appear anywhere in the sky. Image credit: Dr. Tony Phillips [Larger image]

“We expect to see about 20 meteors per hour when the shower peaks on Tuesday morning, Oct 21st,” says Bill Cooke, the head of NASA’s Meteoroid Environment Office.  “With no Moon to spoil the show, observing conditions should be ideal.”

Because these meteors streak out of the constellation Orion, astronomers call them “Orionids.”

“The Orionid meteor shower is not the strongest, but it is one of the most beautiful showers of the year,” notes Cooke.

The reason is its setting: The shower is framed by some of the brightest stars in the heavens. Constellations such as Taurus, Gemini and Orion provide a glittering backdrop for the display.  The brightest star of all, Sirius, is located just below Orion’s left foot, a good place to point your camera while you’re waiting for meteors.

An Orionid meteor streaks over the city lights of Shanghai in 2009. Credit: Jefferson Teng

To see the show, Cooke suggests going outside one to two hours before sunrise when the sky is dark and the constellation Orion is high overhead. Lie down on a blanket with a broad view of the heavens.  Although Orionids emerge from a small area near the shoulder of Orion, they will spray across the entire sky.

2014 Orionid Meteor Shower – NASA Science

Colorful Lunar Eclipse – NASA Science

See the link for info about the turquoise band.

Colorful Lunar Eclipse – NASA Science

On Wednesday morning, Oct. 8th, not long before sunrise, the bright full Moon over North America will turn a lovely shade of celestial red.  It’s a lunar eclipse—visible from all parts of the USA.

“It promises to be a stunning sight, even from the most light polluted cities,” says NASA’s longtime eclipse expert Fred Espenak. “I encourage everyone, especially families with curious children, to go out and enjoy the event.”

Colorful Lunar Eclipse – NASA Science

Shine on, shine on Harvest Moon, up in the sky… 9/8

The Sky This Week, 2014 September 2 – 9 — Naval Oceanography Portal

Full Moon occurs on the 8th at 9:38 pm Eastern Daylight Time.  The Full Moon that occurs closest to the Autumnal Equinox is popularly known as the Harvest Moon.  This year the Full Moon of September beats the October Full Moon by one day for this distinction.  In addition to a catchy name, the Harvest Moon also describes a phenomenon that occurs at this time of the year in which the times of successive moonrises around the time of Full Moon differ by about half an hour instead of the more usual one hour.  This effect becomes more noticeable in more northerly latitudes; residents of Stockholm in Sweden see successive moonrises just over 20 minutes later each night.  Folks in Tromsø, Norway will find Luna rising at about the same time for the nights around Full Moon; north of about 70 degrees latitude Luna actually rises earlier for several nights!  This phenomenon once assisted farmers bringing in their crops by providing the light of the rising Moon to assist them in their labors, allowing them to work late into the night.

The last few weeks of astronomical summer produce another subtle change in the night sky.  This is one of two times during the year that the length of daylight changes at its most rapid rate.  In the spring we all notice the days getting longer, and now we see the opposite effect.  Most of us notice this at the time of sunset, which occurs about two minutes earlier each day as we approach the equinox.  Since the stars set four minutes earlier each day throughout the year, the net effect is that the constellations seem to slow their passage across the sky in the fall, so the stars of summer will seem to linger with us well into November.

The Sky This Week, 2014 September 2 – 9 — Naval Oceanography Portal

Happy Aphelion!

The Sky This Week, 2014 July 1 – 8 — Naval Oceanography Portal

Earth reaches aphelion, its farthest point from the Sun, on the 3rd at 4:13 pm EDT.  At this time we’ll be just over 94,550,000 miles (153,000, 000 kilometers) from the day-star.  Six months from now, in early January, we’ll find ourselves closest to the Sun by a mere 3 million miles or so.  Fortunately this annual excursion means that the planet’s orbit is nearly circular, so our climate remains relatively benign throughout the year.

The Sky This Week, 2014 July 1 – 8 — Naval Oceanography Portal

A New Meteor Shower early on May 24th?

Peak starts near midnight in New Mexico.

The Sky This Week, 2014 May 20 – 27 — Naval Oceanography Portal

The waning crescent Moon shouldn’t be a factor for skywatchers in most of North America on the night of the 23rd and the early morning of the 24th.  With a little luck and clear skies we should have a ringside seat to see a brand-new meteor shower during this time.  We can thank a small, dim comet known as 209P/LINEAR for this potentially spectacular show which should peak somewhere between 2:00 and 4:00 am on Saturday morning here in the Washington area.  The comet was discovered in 2004 in a roughly 5 year orbit that takes it out to the vicinity of Jupiter, whose large gravity field controls the comet’s destiny.  The comet itself will pass about 5 million miles from Earth on the 29th, but on Saturday morning we should plow headlong into a stream of dust that sputtered off the comet’s nucleus at an unseen return from some 200 years ago.  Various meteor experts predict that a single observer at a dark-sky site should see anywhere from 30 to 200 meteors per hour during the peak of activity.  Unlike the more famous Perseids or Leonids, these “shooting stars” will be quite slow, actually looking like a star falling from the sky.  The shower radiant will be in the obscure northern constellation of Camelopardalis, the Giraffe, to the left of Polaris, the North Star.  The best way to enjoy the show is to set up a lawn chair with your feet pointing to the northwest horizon, bundle up against the cool night air, grab some coffee, and look up.  If the predictions hold you could be in for quite a treat.

The Sky This Week, 2014 May 20 – 27 — Naval Oceanography Portal

A New Meteor Shower in May? – NASA Science

The shower is the May Camelopardalids, caused by dust from periodic comet 209P/LINEAR.  No one has ever seen it before, but this year the Camelopardalids could put on a display that rivals the well-known Perseids of August.

“Some forecasters have predicted more than 200 meteors per hour,” says Cooke. 

Comet 209P/LINEAR was discovered in February 2004 by the Lincoln Near-Earth Asteroid Research project, a cooperative effort of NASA, the Massachusetts Institute of Technology Lincoln Laboratory, and the US Air Force.  It is a relatively dim comet that dips inside the orbit of Earth once every five years as it loops around the sun.  

Two years ago, meteor experts Esko Lyytinen of Finland and Peter Jenniskens at NASA Ames Research Center announced that Earth was due for an encounter with debris from Comet 209P/LINEAR.  Streams of dust ejected by the comet mainly back in the 1800s would cross Earth’s orbit on May 24, 2014.  The result, they said, could be a significant meteor outburst. 

Other experts agreed, in part. There is a broad consensus among forecasters that Earth will indeed pass through the debris streams on May 24th. However, no one is sure how much debris is waiting.  It all depends on how active the comet was more a century ago when the debris streams were laid down. 

“We have no idea what the comet was doing in the 1800s,” says Cooke.  As a result of the uncertainty, “there could be a great meteor shower—or a complete dud.”

The best time to look is during the hours between 6:00 and 08:00 Universal Time on May 24th or between 2 and 4 o’clock in the morning Eastern Daylight Time.  That’s when an ensemble of forecast models say Earth is most likely to encounter the comet’s debris.  North Americans are favored because, for them, the peak occurs during nighttime hours while the radiant is high in the sky.

“We expect these meteors to radiate from a point in Camelopardalis, also known as ‘the giraffe’, a faint constellation near the North Star,” he continues.  “It will be up all night long for anyone who wishes to watch throughout the night.”

Indeed, that might be a good idea.  Because this is a new meteor shower, surprises are possible. Outbursts could occur hours before or after the forecasted peak.

In case of a dud, there is a consolation prize.  On May 24th the crescent Moon and Venus are converging for a tight conjunction the next morning, May 25th. Look for them rising together just ahead of the sun in the eastern sky at dawn.

“That’s a nice way to start the day,” says Cooke, “meteors or not.”

A New Meteor Shower in May? – NASA Science

The Pink Moon — lunar eclipse

In Albuquerque, go outside at 1:47am or thereabouts. I’ll be in bed.

The Sky This Week, 2014 April 8 – 15 — Naval Oceanography Portal

Full Moon occurs on the 15th at 3:42 am Eastern Daylight Time.  April’s Full Moon is variously known as the Grass Moon, Egg Moon, Fish Moon, and Pink Moon.  This last appellation will be particularly appropriate this year as Luna undergoes a total eclipse by the shadow of the Earth. …

The Moon will enter the Earth’s penumbral shadow at 12:54 am EDT, marking the beginning of the event.  Most of us probably won’t notice anything unusual until about 45 minutes later when Luna’s disc will begin to show a subtle darkening along her northwestern limb.  At 1:58 am the transit through Earth’s umbral shadow begins, and over the next hour the Moon plunges ever deeper into it.  At 3:07 am the total phase begins, with mid-eclipse occurring at 3:46 am.  The total phase ends at 4:25 am, and Luna exits the shadow at 5:33.  The final traces of the penumbral shadow clear the Moon’s face at 6:38 am, shortly after sunrise.  As to what the Moon will look like during the total phase, that’s anybody’s guess.  This is one of the things that makes watching these eclipses interesting.  The darkness of the Moon’s disc depends very heavily on the clarity of the Earth’s atmosphere, so a bright, coppery-hued Moon means that the air over the Southern Hemisphere is clear.  If you miss this one, don’t fret; we’ll get another eclipse (at a far more decent evening hour) on September 28, 2015.

[Bonus:] Ruddy Mars is now at the peak of his current apparition. He reaches opposition on the 8th, when Earth passes between the red planet and the Sun. At this time he’ll rise at sunset and set at sunrise, remaining visible in the sky all night long. Earth and Mars are closest together on the 15th, when just over 57 million miles (92 million kilometers) separate us. This is the time to try to see details on his far-flung surface, views of which have tantalized earthbound astronomers for centuries.

The Sky This Week, 2014 April 8 – 15 — Naval Oceanography Portal

Happy Spring Equinox!

Get out!

The Sky This Week, 2014 March 18 – 25 — Naval Oceanography Portal

The Vernal Equinox will occur on the 20th at 12:57 pm EDT despite any appearances to the contrary. At that instant the center of the Sun’s disc crosses the celestial equator above a spot located over the southern reaches of Colombia in South America. If the sun were a pinpoint of light and the Earth was a perfect sphere with no atmosphere all parts of the planet would experience exactly 12 hours of daylight and night; but the Sun subtends a disc of about 30 arcminutes’ diameter, the Earth is kind of lumpy, and we have an atmosphere. All of these factors combine to produce days and nights of “equal night” that fall a few days before the equinox, depending on location. Here in Washington our “equal night” fell on St. Patrick’s Day, so despite the snow storm daylight will exceed night from now until a few days after the autumnal equinox. We know that warmer weather will soon follow!

The Sky This Week, 2014 March 18 – 25 — Naval Oceanography Portal