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By Jupiter!

A blog about the stars, astronomy gifts, and other starry musings by the folks behind Indigo Night.

Some Revolutionary Thoughts about the Equinox

by Grant Johnson
September 17, 2016
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Welcome, Indigo Night Sky watchers. This week, the Autumnal Equinox occurs on Thursday, the 22 at 10:21 a.m., EDT.

Our blog post is focused on the equinox, but will also mention a few celestial sights visible this week – if you are willing to stay up late enough.

In common usage, the word equinox refers to the two diurnal cycles in the course of a year (one in spring, one in fall) when the duration of daylight is approximately equal to the duration of night – 'equi' meaning 'equal,' and 'nox' meaning 'night.'  More precisely, the moment of the autumnal equinox is when the sun appears to cross the celestial equator, heading southward. Due to the sun's direction of motion at this time, the event is also called the southward equinox, in contrast to the northward equinox, which occurs at the start of spring. The celestial equator can be understood as the Earth's equator projected outward to become the equator of the celestial sphere, the massive, hollow ball with the Earth at its center that serves as a useful model for mapping and predicting the apparent motion of 'fixed' stars as seen from our home planet. On the days of equinox, the sun rises directly in the east and sets directly in the west. Prior to the autumnal equinox, the sun has been rising and setting more to the north, resulting in summer for the northern hemisphere, and winter for the southern hemisphere. From the autumnal equinox forward, the sun will rise and set more and more to the south, bringing winter north of the equator, and summer to the south.

Due to its occurrence at the time of harvest in the northern hemisphere, the autumnal equinox has often been associated with festivals celebrating the fruits of agricultural labor, but my favorite association with this special day is that the French First Republic that was proclaimed (and the monarchy abolished) on September 21, 1792. Thus, the following day, September 22, 1792, which was the day of the autumn equinox that year (exactly 224 years prior to this year's autumnal equinox), became the first day of the 'Republican Era' in France.

This alignment of civic life to astronomy resonates for me in at least three meaningful ways. The first is that it represents the French Republic's commitment to science and rational thought as appropriate bases for sound governance. Understanding of astronomy had been growing at a rapid pace over the previous hundred years, largely due to the contributions of Isaac Newton at the start of the 18th century. By tying the start of the Republic to the equinox, the French made a bold statement of their faith in reason. The second powerful meaning in this equinoctial start to the Republic is that is demonstrates France's decisive turning away from the Sun Kings by letting the start of the nations's new republican day be determined by the movements of the real sun, instead.  And finally, the choice of the equinox for the first day of the French Republic highlights the importance of égalité – 'equality' – as one of the three fundamental concepts driving the revolution (liberté, égalité, fraternité was the rallying cry: 'liberty, equality, fraternity'). To begin the new national government on the day of equal light and darkness was a profoundly meaningful choice, and although the Republican Calendar did not endure, I always enjoy recalling it as the autumnal equinox marks the onset of fall.

 

A rare and beautiful automata work, this Republican Clock has both Republican and Gregorian dials and others that indicate the age and phase of the moon, time of sunrise and sunset, equation of time, world time and signs of the zodiac.  The clock synced with the Republican Calendar, in use between 1793 and 1805, designed in part to remove all religious and royalist influences.

As for celestial objects visible with the naked eye this week, the best bets are between about 10:30 p.m. and dawn each night. The waning moon, rising a little later each night through the week, reaches last quarter on Thursday, the day of the equinox. Early on the 23 – at roughly 2 a.m. for mid-northern latitudes – the quarter moon rises in Orion, surrounded by the bright stars and star clusters of Taurus, Gemini, and Auriga. If I was going to lose some sleep for the stars this week, I would pick that night to do it. Thanks for stopping by, and keep looking up. GEJ

The Sky This Week

by Grant Johnson
September 12, 2016
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Welcome, Indigo Night Sky Watchers.

This is another good week to see bright celestial lights in the early dark immediately following 'nautical twilight' – when the center of the sun's disk passes 12° below the horizon . . . nightfall.   The horizon is still faintly visible at that time, but it's dark enough to see the stars. (During 'nautical twilight' the illumination level is such that the horizon is still visible even on a moonless night allowing mariners to take reliable star sights for navigational purposes, hence the name.)

Each of these nights – as it has been for some time and will continue to do – Venus shows forth at the western horizon in its 'Evening Star' aspect for just a few minutes after sunset. The main event, however, is the appearance of the full 'Harvest' moon late in the week. Following its familiar retrograde path through the zodiac, the moon rises a bit later and more fully illuminated each evening, reaching full brightness on Friday, the 16th, when it faces the sun along the same solar radius as the earth. All the while, Saturn and Mars continue their pas de deux in Ophiuchus, where they stand above south when the full moon rises at dusk. Have a wonderful week, and keep looking up.

Most Excellent Scrabble Word

by Grant Johnson
September 05, 2016
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Greetings, watchers of the Indigo Night. This will be another rewarding week for naked eye viewing of the heavens in mid-northern latitudes. The sky will grow dark a few minutes before 9 p.m. (slightly earlier each evening) over the next few days, and as we get into the later part of the week, the by now familiar pairing of Saturn and Mars in Ophiuchus will be joined by the waxing moon on its way to first quarter Friday. Wednesday through Friday, the two bright planets and the moon will be in close conjunction – an arrangement often referred to as a 'syzygy.'

Many readers may know that this term has a strict sense and a looser sense, and it is the latter that we use to describe this close grouping of three non-stellar bodies. Bright star Antares – the 'Rival of Mars' – will shine just below the lunar-planetary syzygy, a celestial punctuation mark to the formation's elegant progress.

At night the stars put on a show for free.

by Grant Johnson
August 15, 2016
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Week of August 15 – August 21

 

There's no need for stargazers to set an alarm for the wee hours this week, as the sky will offer especially satisfying celestial views from nightfall until about 1am. Even with a brightly illuminated moon throughout the next seven days, two close planetary pairings should still be visible to many viewers at dark, Monday through Thursday in most mid-northern latitudes. And on Thursday itself, the full 'Lightning' moon will rise at dusk and travel across the night sky to morning.

 

The first of the two planetary pairings mentioned above brings together Mercury and Jupiter in a close approach as they light from Leo and Virgo, respectively. They will show at the western rim in mid-north latitudes for a few moments after dark in the first part of the week, disappearing fairly quickly as they follow the sun over the western horizon. The other pairing, which finds Mars and Saturn in Scorpius and Ophiuchus, respectively, is more spectacular, joined as it has been for a number of weeks by bright star Antares, the 'Rival to Mars,' and 'Heart of Scorpius.' This celestial triad, slowly expanding and contracting with its planetary members' orbital progressions, is a radiant herald for the week's brilliant moon, rising before them slightly earlier each night.

 

Viewing S, late evening.  Mars and Saturn join the red giant Antares.  

Most of the celestial show this week is in prime time, so make a point to get outside, look up, and see some stars.

Watching the summer sky

by Van Wymelenberg
June 24, 2016
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Guest Post by Glen Ward / Starry Mirror

Hello Stargazers —

A wonderful event is occurring in the heavens early this Summer, and you can see it with your own eyes on any clear evening.

The planet Mars has just experienced an “opposition.”   And what’s more, it’s hanging up there close to a couple of other old friends: Saturn and the bright star Antares!

“Opposition” is just a fancy way of saying that the Earth is passing between Mars and the Sun. Our planet is a bit closer to the Sun than Mars, and every two years or so we catch up to the Red Planet, overtake it, and keep on going around. For a few weeks around opposition, Mars gets very bright and becomes large enough to show details in small Earthbound telescopes.  The patient observer -- retuning for a look every few nights over the course of the next month or so -- will also see the red planet go retrograde -- appear to move backwards against the background of fixed stars.  This effect is really wonderful to behold.  The old ZigZag.  I think that's what Aristotle called it.

This Summer, if you go outside shortly after dark and you look low in the South, you can’t miss Mars. It is a bright orange “star,” the brightest star in the Southern sky. Look a little to its left, and you will see two other bright stars. The higher up of this pair is none other than Saturn, and the lower star is Antares, in Scorpius. Antares’ name means the “anti Mars,” or the “equivalent of Mars.” So, Mars is meeting its twin – or its nemesis – this Summer!

Most of the time, Mars is no brighter than Antares, and they look almost identical in color and brightness. But during this time of opposition, Mars is much brighter. In late April, Mars approached very close to Antares heading Eastward, and the planet came to a standstill. Then it began moving West, to the right, against the stars. This is the famous zig-zagging “retrograde motion” for which Mars is famous, and which is really caused by the Earth’s own motion in “passing up” Mars. By early July, Mars will begin moving Eastward again – to the left - against the starry backdrop. So, in late August Mars will appear to pass very close to Antares for its second time this year!

These days, most new learning about Mars comes from space probes. But astronomers around the world still enjoy watching the planet around opposition. During the Golden Age of Observational Astronomy – the Victorian Era – Earthbound observation of Mars was a new frontier. Astronomers of the time gave fanciful names to the mysterious green shadings seen on the planet, like the Juventae Fons (Fountain of Youth,) the Solis Lacus (Lake of the Sun,) or the Syrtis Major (after the Gulf of Sidra, in Libya.) And, the astronomer Percival Lowell imagined these features were part of a planet-wide system of waterways which he believed indicated an intelligent Martian civilization. Today we know that there are no canals, lakes or gulfs on Mars, and these areas are mostly just “albedo features” - areas of darker shading. But, astronomers still enjoy looking for these famous Martian locales. Watching the Red Planet gives us a link to the times when there was more mystery, more room for romantic ideas, in science.

Let’s not forget about our friend Saturn, which is spending all of 2016 hanging out above Antares. It’s a yellow “star,” just a little brighter than Antares. Because Saturn is so much more distant than Mars, it appears to move against the starry backdrop much more slowly. Saturn was at opposition in early June, but the ringed planet’s great distance means that opposition makes only a little difference in how big and bright it looks. Still, the planet and its rings are a pretty sight in even very small telescopes. If you have any little telescope around, no matter how humble, try pointing it at Saturn. You may get a surprise you’ll never forget.

If you are outside looking at this great conjunction of stars and planets in the Southern sky, you might notice another very bright-yellow “star” low in the West – It’s Jupiter! The biggest planet will hang out in the evening sky until mid-Summer, before it passes behind the Sun – “conjunction” – in September. Jupiter has four Moons around it which were discovered by Gallileo. Any little telescope or even some binoculars can show these Moons as little stars near the planet, so you might want to check it out.
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Just Because

The night sky print which arrives for no particular reason, other than to celebrate the gift of love that is your beloved, is cherished like no other.

Birthdays

Each of us has a story that begins in a single moment. Poets and philosophers from Shakespeare to Tennyson, from Moore to Jung, share a common fascination with the night sky at the moment of birth, and the idea that the moon and stars stand in timeless, silent witness to this moment.

Wedding Anniversaries

The night sky print, showing the moon and stars just as they appeared on the night you met, the moment of your first kiss, or your wedding night, is an exceptional anniversary gift. Appropriate for any year, especially so for the 1st anniversary, the year of the ‘paper’ gift.

New Baby

The night sky print, showing the moon and stars just as they appeared on the child’s first starry night, with your words – funny, wise, sweet, hopeful, perhaps a favorite quote from a story or song – makes a beautiful keepsake.

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