Sunrise – (earliest) sunset (this Friday)


Earliest Sunset – This week Friday 4:34 and we dwell there for a week. Then sunsets slowly drift later. But sunrise time continues to come later until early January. Orion Capsule scheduled to launch this week – NASA’s unmanned flight test of its big investment in crewed space exploration going forward into the future. Watch the moon track across the sky this week. Friday, it sits amid the face stars of Taurus, right in the ‘V’ at 10p. Jupiter rises at 10p now; Mars still hangin’ in the SW evening twilight.

December 1, 2014


[Dave Heller] Friday marks the earliest sunset of this year — can summer be far away? Let’s consult the calendar with Derrick Pitts, chief astronomer at the Franklin Institute. So Derrick, I’m noticing we’re still a few weeks out from Winter Solstice.

[Derrick Pitts] Yes indeed we are a few weeks out from Winter Solstice, and often there’s some confusion about why we can have the earliest sunset come in early December and the latest sunrise come in early January. Doesn’t that sort of screw around with things? But actually it doesn’t, because our year is 365 days. But the space year — the Earth year, really — 365.242558694738476 days…

… Give or take a, …

… Give or take a numeral here or there.

But therein lies the rub.

But therein lies the rub because the same thing is also true for the day. We make the day 24 hour because it works well on the face of a watch or a clock or anything like that. But really the length of the day is 23 hours, 56 minutes, 4 seconds.

Say, pretty close!

It’s not so bad, but we have to accomodate for that. And one of the ways we accomodate for that is when this earliest sunset is and the latest sunrise comes because the difference between astronomical time and civil time creates these shifts in what happens when.

So what is Winter Solstice?

So Winter Solstice actually is that point when we have the fewest number of minutes of daylight. And that really does happen what we call the 21st of the month. I say “what we call the 21st of the month” because sometimes even that can change with the difference between civil time and astronomical time. This whole situation reverses itself when we get around to Summer Solstice and there’s a sequence in which all this stuff goes through the course of the year. But, not to worry — everything will be just fine because, as I often say, once we get past this point in early December, well in another week we’ll start seeing sunsets come later and later and later. Spring is only around the corner.

I like it. Hey — no holiday slowdown for NASA. They’re getting ready to launch an unmanned test flight.

Indeed they are. NASA has developed a new crew capsule that is designed to carry astronauts onto the moon and off to Mars at some time in the future. And that flight test will launch this capsule on board what’s called a Delta 4 heavy lift launch vehicle, loft it up into space, take it up to a maximum altitude of 3,600 miles, and then after two orbits, take it back down for a splash reentry into the Pacific Ocean. They first want to test the launch system delivery, getting this payload into orbit. They also want to check how all the separations take place between the various components of the craft as it flies into space. And primarily they want to be able to test the heat shield that needs to withstand 5,000 degrees of re-entry temperature. And they also want to test the parachutes that will be deployed once it re-enters the Earth’s atmosphere, heading towards splash down, to see if those parachutes will adequately slow the craft down as it comes down to a watery landing in the Pacific ocean. The Orion flight test launch is at about 7:05 in the morning on Thursday. It only lasts about 4.5 hours, so the whole test will be over at 11:30. If you’d like to participate in some activities surrounding this, over at the Franklin Institute we’ll have great stuff going on Wednesday during the day and also on Thursday we’ll be monitoring the flight live, and I’ll be providing some color commentary. So come on over and join us there.

Bring your own popcorn.

And some for me, too!

  • The Orion Spacecraft moves by the Vehicle Assembly Building on its approximately 22 mile journey from the Launch Abort System Facility at the Kennedy Space Center to Space Launch Complex 37B at the Cape Canaveral Air Force Station, Tuesday, Nov. 11, 2014, in Cape Canaveral, Fla. The test flight for Orion is scheduled to launch on Dec. 4.(AP Photo/John Raoux)

Derrick, we have a moment left — weather permitting, what’s available to be seen in the Cyber Monday sky?

You know what’s really cool is that Mars is still hanging on in the southwest, looking great right at twilight in the evening and after the sun sets and the sky’s getting darker. But we should actually watch the moon as it tracks across the night sky this week, because Friday it’s going to sit right among the stars of the face of the constellation Taurus the Bull. Now that’s a v-shaped arrangement of stars, and right about at 10:00 the moon’s going to be right smack in the middle of this “V”, so it should be a great view to see how all this works. And if you were wondering how to find the constellation Taurus, well, the moon’s going to be there on Friday night, and of course Taurus is one of the leading constellations of the winter star group. So down toward the eastern horizon below Taurus you’ll find Orion, and of course if you’re still looking at the sky an hour later, you’ll find Jupiter is well up above the eastern horizon as Jupiter rises now at 10 p.m. So around 11 p.m. it’ll be high enough to view easily, and of course it’ll be visible all night long.

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