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The day – from one solar noon to the next – is longest around now

This curved line is called an analemma.  It shows sun's declination - its annular distance from the celestial equator - and difference (in minutes) between time as measured by the clock and time as measured by the sun.  Click here to read more about this image.

This curved line is called an analemma. It shows sun’s declination – its annular distance from the celestial equator – and difference (in minutes) between time as measured by the clock and time as measured by the sun.

Happy solstice, everyone. The December solstice will come tomorrow at 23:03 Universal Time. At this instant, it’ll be at 5:03 p.m. for the Central U.S., or around sunrise for North and south America, sunset for far-eastern Asia, midnight for Africa and Europe, and noontime over the Pacific Ocean. We in the Northern Hemisphere will have our shortest day and longest night of the year. And yet – if you consider the word day in another light – the longest days of the year come each year in December for the entire globe.

Wisdom has a new egg!

Wisdom

Wisdom and her new egg. Photo by Greg Joder via USFWS Pacific Region on Tumblr

Awesome news! A Laysan albatross named Wisdom – said to be the world’s oldest known, banded, wild bird at an estimated age of 63 – has been photographed (December, 2014) incubating her newest egg. Go, Wisdom! Still breeding at 63!

Milky Way above Navajo sandstone in Arizona

View larger. | The Milky Way as seen from Vermilion Cliffs National Monument in Arizona, by Dave Lane Astrophotography.  Visit Dave Lane's Facebook page.

The Milky Way as seen from Vermilion Cliffs National Monument in Arizona, by Dave Lane Astrophotography.

Here is a 16-image panorama of the Milky Way arced above a little known area in northern Arizona – called White Pocket, in the Vermilion Cliffs National Monument. Those with a four-wheel drive vehicle can see this spectacular landscape of twisting Navajo sandstone.

Help name craters on Mercury

A limb view showing the northern part of the 1,640 kilometer- / 1,018-mile-wide Caloris Basin within the Raditladi Quadrangle in the northern hemisphere on Mercury.  MESSENGER acquired this image on October 18, 2014.  Read more about this image from Andrew R. Brown.

A limb view showing the northern part of the 1,640 kilometer- / 1,018-mile-wide Caloris Basin within the Raditladi Quadrangle in the northern hemisphere on Mercury. MESSENGER acquired this image on October 18, 2014. Image via NASA / JHU / APL MESSENGER spacecraft.

The outreach team of NASA’s MESSENGER spacecraft has organized a competition to name five impact craters on Mercury. Submit your ideas before January 15, 2015. Names chosen as finalists go to the IAU for selection of the five winners. Details inside.

Ursid meteors active around December solstice

Ursid meteors radiate from very far north on the sky's dome, near the Big and Little Dippers.

Ursid meteors radiate from very far north on the sky’s dome, near the Big and Little Dippers.

The annual Ursid meteor shower always peaks near the time of the December winter solstice, so, in 2014, look for some possible activity over the next several nights. This shower favors the more northerly latitudes in the Northern Hemisphere, but even at far northerly latitudes, it’s generally a low-key production, not nearly as exciting as the Quadrantids in early January.

Why do most evergreen trees have a pyramid shape?

evergreen trees conifers

Photo credit: Bill Abbott/Flickr

Those who admire the shape of a Christmas tree might like to know that its shape has evolved in response to wind, snow, and light.

Northern Cross stands upright in west on December evenings

The Northern Cross stands upright in the west on December evenings.

The Northern Cross isn’t as famous as its counterpart – the Southern Cross – visible from the Southern Hemisphere or the northern tropics. But the Northern Cross also looks like a cross, and it’s pretty easy to spot. It’s a large, noticeable star pattern.

The star Deneb marks the top of the Northern Cross, and the star Albireo marks the bottom. Tonight you can find the Northern Cross shining fairly high in the west at nightfall, as seen from mid-northern latitudes. It sinks downward during the evening hours, and stands proudly over the west-northwest horizon around mid-evening.

The Northern Cross is what’s known as an asterism. In other words, it’s not a constellation but simply a noticeable pattern of stars. It’s part of the constellation Cygnus the Swan.

Big iceberg in South Atlantic

The Aqua satellite caught this image of the unnamed iceberg on December 3, 2014.  Image via NASA Earth Observatory.

Landsat 8 acquired this image of an unnamed iceberg adrift in the South Atlantic Ocean on December 3, 2014. Image via NASA Earth Observatory.

On December 3, 2014, satellite images revealed a large iceberg – measuring about 165 square kilometers (64 square miles) – east of the southern tip of South America in the South Atlantic Ocean. This iceberg doesn’t meet the criteria for tracking or naming. NASA Earth Observatory said:

Only icebergs that have a side measuring at least 19 kilometers (12 miles) long are named and tracked by the U.S. National Ice Center. That means nearly round or square icebergs—like the one pictured above—can be quite large and still not meet the criteria for naming and tracking.

Comet Finlay is in outburst!

View larger. | Comet Finlay, via Bob King at Universe Today.  Used with permission.

Nightly position of Comet Finlay from December 18 to January 12. Chart via Bob King at Universe Today, and via Chris Marriott’s SkyMap software. Used with permission.

Comet 15P/Finlay has gotten suddenly brighter. It’s brighter than it was expected to be, at its brightest, for this return near the sun. If you have a small telescope or large binoculars, you can now catch Comet Finlay now in the sky after sunset, not far from the place where the sun went down. It will be very near the planet Mars on December 23 and 24, 2014.

Winter solstice as seen from Stonehenge

Winter solstice sunset at Stonehenge in the mid-1980s. Image via Wikimedia Commons.

Many travel each year to Stonehenge in England – perhaps the most famous of the ancient astronomical monuments found around the world – to be present on the day of the northern winter solstice, which is coming up this Sunday. Most who travel to Stonehenge visit the site early in the morning, to watch as the sun rises above the stones.