Great stuff, as usual, from The Sky This Week.

This is a good week to try to make sense of the sheer scale of the cosmos as we have a variety of bright objects that we can look at and think of in terms of distance as well as brightness. The first thing we need to do is find a convenient “measuring stick”, and fortunately the laws of physics provide us one that’s good for measuring vast distances. Light, the essential “messenger” of all celestial objects, travels at a finite speed that amounts to about 300,000 kilometers (186,000 miles) per second, so if we can measure the time it takes light to reach us from an object we can gauge its distance.

When we look at the Moon, we see it as it appeared a just over a second ago. Light from the Sun takes eight minutes to get from there to here. The ruddy glow of Mars is five minutes old by the time it arrives here at earth. Giant Jupiter’s bright glow has taken 50 minutes to cross the gulf of space that separates us. … Our last bright planet is Saturn, and the view you’ll get of his wonderful rings tonight will take 77 minutes to get here. Far-flung Pluto, which marked the edge of the solar system when I was in school, is still relatively close-by, just under 4.5 hours at light speed.

Now let’s jump to the rising stars of the summer Triangle in the eastern part of the sky. Bright Vega, highest and brightest star of the trio, is located at a distance that takes light 27 years to cross! Altair, southernmost of the three stars, is even closer, a mere 16 “light years” away. Looking at the last, northernmost member of the triangle one would naturally assume that Deneb would be a similar distance from Earth, but here is where assumptions break down. Vega and Altair are relatively bright “normal” stars, but Deneb is a “blue supergiant” star that shines with the equivalent light of 100,000 suns! Its distance is some 100 times farther away than Altair, so the light you see from it tonight started its journey toward us when Constantine was Emperor of Rome. And we’ve barely ventured into the vast starfields of the Milky Way.

from The Sky This Week

From The Sky This Week: The Moon waxes in the evening sky this week, passing through the summer constellations along the southern reaches of the ecliptic. Full Moon occurs on the 20th at 7:02 am Eastern Daylight Time. June’s Full Moon is popularly known as the Strawberry Moon, Rose Moon, Mead Moon, and Honey Moon. Each of these names not only indicates something indicative of the month’s flora, they also refer to the warm tone that the Moon can take on a warm June evening due to her southerly declination. Look for the Moon a few degrees north of the bright star Spica on the evening of the 14th. On the 16th and 17th she accompanies ruddy Mars across the sky, and on the 18th she passes just over two degrees north of yellow-hued Saturn.

The summer solstice falls on the 20th at 6:34 pm EDT. At this time the center of the Sun’s disc stands directly over the Tropic of Cancer north of the Hawai’ian Islands. While astronomers consider this to be the first day of summer, many traditional calendars observe it as “Midsummer’s Day”, commemorating the year’s longest day. Here in Washington Old Sol is above the horizon for 14 hours 54 minutes. Add in the times of morning and evening twilight and the duration of astronomical darkness amounts to a paltry 5 hours 8 minutes. The farther north you go, the less the duration of night becomes. Cities such as Paris and London never experience total darkness at this time of the year, and places north of the Arctic Circle see the Sun above the horizon for a full 24 hours. The Sun appears to hover near the Tropic of Cancer for a week or so around the time of the solstice, and most of us probably won’t notice the changing times of sunrise and sunset until well into July.

http://www.usno.navy.mil/USNO/tours-events/sky-this-week/the-sky-this-week-2016-june-14-21

Goodbye to Night: 80 Percent of Humanity Lives Under Light Polluted Skies By Carl Engelking | June 10, 2016 12:59 pm

The beauty of the night sky is rapidly fading, and an update to the first global light pollution map, created 15 years ago, makes that painfully clear.

The new atlas revealed that more than 80 percent of the world lives under light-polluted skies – that rises to 99 percent of the population in the United States and Europe. One-third of humanity can no longer see the Milky Way. As the new map shows, the night sky is slowly retreating to the glow of artificial light.

In Mountain DST, the vernal equinox is 10:30pm 3/19.

The Sky This Week, 2016 March 15 – 23 — Naval Oceanography Portal

The vernal equinox occurs on the 20th at 12:30 am EDT. This is the moment when the Sun’s ecliptic longitude reaches zero degrees. For many ancient cultures this moment marked the beginning of a new year ….

Full Moon, which occurs on the 23rd at 8:01 am Eastern Daylight Time. The Full Moon of March is popularly known as the Worm Moon, Crow Moon, Sap Moon, or Lenten Moon.

The Sky This Week, 2016 March 15 – 23 — Naval Oceanography Portal

The Sky This Week, 2016 February 16 – 23 — Naval Oceanography Portal

The Moon waxes through her gibbous phases this week, with Full Moon occurring on the 22nd at 1:20 pm Eastern Standard Time. February’s Full Moon is popularly known as the Snow Moon or Hunger Moon, indicative of the harsh weather that often accommodates the year’s shortest month. Look for the Moon near the bright star Regulus on the evenings of the 21st and 22nd. On the 23rd she cozies up to bright Jupiter, with less than two degrees of space between them.

The Sky This Week, 2016 February 16 – 23 — Naval Oceanography Portal

Five planets paraded across the dawn sky early Wednesday in a rare celestial spectacle set to repeat every morning until late next month.

Headlining the planetary performance are Mercury, Venus, Mars, Saturn and Jupiter. It is the first time in more than a decade that the fab five are simultaneously visible to the naked eye, according to Jason Kendall, who is on the board of the Amateur Astronomers Association of New York.

Admission to the daily show is free, though stargazers in the Northern Hemisphere should plan to get up about 45 minutes before sunrise to catch it.

How to View Five Planets Aligning in a Celestial Spectacle – The New York Times

The Sky This Week, 2016 January 19 – 26 — Naval Oceanography Portal

The Moon brightens the chilly overnight hours this week. Full Moon occurs on the 23rd at 8:46 pm Eastern Standard Time. … January’s Full Moon is popularly known as the Moon after Yule, the Old Moon, or the Wolf Moon.

The Sky This Week, 2016 January 19 – 26 — Naval Oceanography Portal

For the first time in a decade, you can see 5 planets aligned without a telescope

For the first time in more than a decade, Mercury, Mars, Venus, Saturn, and Jupiter — the five planets bright enough to be seen with an unaided eye — will all be visible at once in the sky.

You’ll have to wake up early to catch it. Starting January 20, it will be possible to see all five planets in a row, about 45 minutes before sunrise, Sky and Telescope reports. The planets should be visible in this arrangement until February 20.

(Sky and Telescope notes it might get harder to see Mercury after the first week of February, because of its low position near the horizon).

For the first time in a decade, you can see 5 planets aligned without a telescope

The Sky This Week, 2015 December 29 – 2016 January 5 — Naval Oceanography Portal

The latest sunrise of the year occurs on January 5th, when Old Sol crests the horizon at 7:27 am EST here in Washington, DC. On that same evening sunset occurs at 5:00 pm, 14 minutes later than its earliest sunset back on December 7th. The total length of daylight on New Year’s Day will be 9 hours 30 minutes, four minutes longer than it was on the day of the solstice, and the days will steadily increase in length until the summer solstice, which will fall on June 20.

The Sky This Week, 2015 December 29 – 2016 January 5 — Naval Oceanography Portal

The Sky This Week, 2015 December 29 – 2016 January 5 — Naval Oceanography Portal

January 2nd marks the date of Earth’s perihelion, its closest distance to the Sun. On this date we’ll be a mere 147 million kilometers (91.4 million miles) from the fierce surface of the “day star”.

The Sky This Week, 2015 December 29 – 2016 January 5 — Naval Oceanography Portal

The Sky This Week, 2015 October 27 – November 3 — Naval Oceanography Portal

The bright planets are now confined to the morning sky where you’ll find Venus and Jupiter dominating the view before sunrise. The two planets had a spectacular conjunction on the 26th, and while Venus draws away from the giant planet the pair will remain a beautiful sight to the naked eye. If you look carefully you’ll see the much fainter ruddy glow of Mars just below the brighter pair. Over the course of the week Venus will close in on the red planet, and early risers on the 3rd will see them less than a degree apart. This sight will be worth getting up early for; just remember that it will be best seen at around 5:00 am Standard Time!

The Sky This Week, 2015 October 27 – November 3 — Naval Oceanography Portal

The Sky This Week, 2015 October 27 – November 3 — Naval Oceanography Portal

Since it occurs about mid-way between the autumnal equinox and the winter solstice, Halloween is known as a “cross-quarter day” that was celebrated widely in Europe before the influence of Christianity took hold. This early observance was known as Samhain and was celebrated as a harvest festival marking the boundary between the days of light and the nights of winter’s darkness. It was also thought to be a time when the boundary between the worlds of the living and the dead drew closest, so a large part of the celebration included honoring ancestors and others who had passed into the underworld. When Christianity swept northern Europe the festival was incorporated into the feats of All Saints’ Day, which traditionally fell on November 1st. Carving a Jack O’ Lantern is a part of the tradition, imitating illuminated gourds and turnips lit to welcome the spirits of the dead to enter a home and partake of food and drink.

The Sky This Week, 2015 October 27 – November 3 — Naval Oceanography Portal

Technically full after midnight, watch for it 10/26 and 10/28, too.

The Sky This Week, 2015 October 20 – 27 — Naval Oceanography Portal

The Moon waxes in the evening sky this week, wending her way through the autumnal constellations as she makes her way eastward along the ecliptic. Full Moon occurs on the 27th at 8:05 an Eastern Daylight Time. October’s Full Moon is popularly called the Hunter’s Moon, and it shares almost the same horizon geometry as September’s Harvest Moon. In far northern latitudes this causes successive moonrises to occur at about the same time on the nights around the full phase, and this “extra” light gave hunters a little more time to pursue game across the stubble of the harvested fields. Some Native Americans referred to it as the Leaf-falling Moon or the Nut Moon. Because the autumn sky is filled with mostly dim, ill-defined constellation patterns Luna’s journey this week is a lonely one; there are no bright objects along her path to meet with.

The Sky This Week, 2015 October 20 – 27 — Naval Oceanography Portal

The Sky This Week, 2015 October 20 – 27 — Naval Oceanography Portal

The main planetary action occurs in the pre-dawn sky with dazzling Venus, bright Jupiter, and a rather subdued ruddy Mars interacting over the next few weeks. You’ll have no trouble watching Venus close in on Jupiter this week. The two planets will be closest together on the mornings of the 25th and 26th when they will be separated by just over one degree. After that Venus will set her sights on Mars, passing the red planet on November 3rd. It’s well worth rising before the Sun to watch this celestial dance through the end of October while we’re still on Daylight Time. After November 1st everything will occur an hour earlier as we return to Standard Time!

The Sky This Week, 2015 October 20 – 27 — Naval Oceanography Portal