12/04/2014 – Ephemeris – What’s happening on the Sun this solar cycle
Ephemeris for Thursday, December 4th. The sun will rise at 8:02. It’ll be up for 9 hours even, setting at 5:02. The moon, 2 days before full, will set at 6:52 tomorrow morning.
It looks like maybe we’ve hit the peak of sunspots in this 11 year solar cycle. Actually this cycle had two peaks, the latter part of 2012 when the world ended. You do remember the world ending two years ago on December 21st. How soon we forget. The second peak in this solar cycle occurred in the first three months of this year. The sunspot cycle 24 so far appears to be the weakest since cycle 12 in the 1880s. The time of the peak can only be determined in hindsight. Of course this weak sunspot cycle produced the largest sunspot group, or active region, as they are now called, in 24 years, so I expect more surprises from this solar cycle. I expect to see more aurorae or northern lights as the sunspot numbers decline.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Sunspot cycle from 2000 until October 2014. Credit: NOAA/SWPC.
All the recorded sunspot cycles back to the 18th century. Credit: Dr. David Hathaway, NASA /ARC.
Here’s a link to NASA’s Sunspot Cycle page with a lot more information.
12/03/2014 – Ephemeris – Bright planets: One early and one late
Ephemeris for Wednesday, December 3rd. The sun will rise at 8:01. It’ll be up for 9 hours and 1 minute, setting at 5:03. The moon, 3 days before full, will set at 5:48 tomorrow morning.
In reviewing which planets are visible tonight, it looks like we’re still down to two. Venus, Saturn and Mercury are hanging around near the direction of the Sun. It will be a little while before we see them again. However we can see Mars, which will be low in the southwest at 7 p.m. It will set at 8:29 p.m. Mars’ setting time will slowly advance only 6 minutes between now and the end of the year. Jupiter will rise at 10:28 p.m. in the east-northeast. The best telescopic views will have to wait a couple of hours after that. So if you’re more of an early bird rather than a night owl it might be better to view Jupiter with a telescope in the morning. Jupiter has those four bright moons that change position daily, and sometimes while you watch.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Mars in the southwest at 7 p.m. December 3, 2014. Created using Stellarium.
A binocular view of what the moon will look like at 7 p.m. December 3, 2014. Created using Stellarium.
Jupiter rising with the winter constellations at 11 p.m., December 3, 2014. We’re actually looking at the eastern half of the sky. Created using Stellarium.
At 6 a.m. December 4, 2014 Jupiter and the winter constellations will swing into the southwest while out of the view the spring and early summer stars take over the eastern sky. Created using Stellarium.
Telescopic view of Jupiter at 6 a.m. December 4, 2014. The moons on the left in order from left to right are Callisto, Ganymede and Europa. In the next hour the moons will appear to get even closer together, especially Ganymede and Callisto. Created using Stellarium.
12/02/2014 – Ephemeris – The unequal dates of latest sunrise and earliest sunset
Ephemeris for Tuesday, December 2nd. The sun will rise at 8:00. It’ll be up for 9 hours and 3 minutes, setting at 5:03. The moon, 3 days past first quarter, will set at 4:41 tomorrow morning.
This evening’s sunset is just a minute from the earliest sunset of the year. The Earliest sunset will actually be on the 9th. However the latest sunrise won’t occur until January 2nd. The reason combines the effects of the tilt of the earth’s axis and the fact that the Earth is only a month from perihelion, its closest to the Sun. Both these effects cause the sun to appear to move faster eastward than average, so the Earth has to rotate a bit farther each day to catch up with the Sun. This makes the sunrise and setting events later than one would expect, so they don’t occur together on the shortest day of the year, the 21st this year. Our sunrise this morning is still 19 minutes earlier than the latest sunrise on January 2nd, 2015.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
This figure 8 is called an analemma. One can find it on old globes in the Pacific Ocean. Explanation below. Created using my LookingUp program for Traverse City, MI near +45° latitude.
The analemma is a graphical representation of a daily value called the Equation of Time. It’s best known use is in corrections to sundial time. The vertical axis is the sun’s declination or north-south position. It is highest at summer solstice and lowest at winter solstice. It is the result of two effects: the tilt of the Earth’s axis to the plane of the Earth’s orbit around the Sun, and the change in the Earth’s velocity around the Sun as the Earth moves from perihelion, its closest to the Sun in early January to aphelion, its most distant in July.
If the Earth’s orbit were circular, and it orbited the Sun at the same speed. The analemma would be skinner and the north and south lobes would be of equal size. Since we’re closer to the Sun in the winter, we move faster than average around the Sun, so it appears to move faster eastward. That combines with the faster appearing movement of the sun crossing the closer hour lines at higher and lower declinations. In the diagram above note that the vertical hour lines are slightly closer together at the bottom and the top, so the Sun, moving eastward each day crosses them quicker. Near the winter solstice the two effects work together making sunrise and sunset trending to be later than normal. For the summer solstice the eastward speed of the sun is slower than normal, because we’re farther from the Sun. This works against the effect of the earth’s tilt but cannot completely negate it, making the top of the loop smaller than the one at the bottom. The arrows show the speed and direction of the Sun at the solstices.
To see real analemmas search for analemma images on the Internet. It takes a year to photograph one.
12/01/2014 – Ephemeris – Previewing December skies
Ephemeris for Monday, December 1st. The sun will rise at 7:59. It’ll be up for 9 hours and 4 minutes, setting at 5:03. The moon, 2 days past first quarter, will set at 3:32 tomorrow morning.
Let’s preview December’s skies. Winter will officially arrive on the 21st at 6:03 p.m., the winter solstice. The noontime sun will dip from 23 ½ degrees to a bit less than 22 degrees above the southern horizon on that day. There will be little movement in the sunset times: In the Traverse City/Interlochen area this will be from 5:03 today, down to 5:02 and then advancing to 5:11 at the end of the month. There is more movement in the sunrise times which will advance from 7:59 this morning to 8:19 on the 31st. The big event in December will be the Geminid meteor shower whose maximum is on the morning of the 14th. But will be hampered by the moon after 12:17 a.m that morning.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Star Chart for December 2014. Created using my LookingUp program.
The Moon is not plotted. The planets and stars are plotted for the 15th at 9 p.m. That is chart time.
Evening astronomical twilight ends at 6:48 p.m. on December 1st, decreasing one minute by the 9th and increasing to 6:57 p.m. on the 31st.
Morning astronomical twilight starts at 6:14 a.m. on December 1st, and increasing to 6:33 a.m. on the 31st.
Add a half hour to the chart time every week before the 15th and subtract and hour for every week after the 15th.
For a list of constellation names to go with the abbreviations click here.
Also shown is the Summer Triangle in red. Clockwise from the top star is Deneb in Cygnus, Vega in Lyra and Altair in Aquila.
The green pointer from the Big Dipper is:
- Pointer stars at the front of the bowl of the Big Dipper point to Polaris the North Star.
The Geminid radiant is shown in yellow and marked GemR.
11/28/2014 – Ephemeris – Not quite a star cluster, but pretty cool nonetheless
Ephemeris for Friday, November 28th. The sun will rise at 7:55. It’ll be up for 9 hours and 9 minutes, setting at 5:04. The moon, 1 day before first quarter, will set at 12:01 tomorrow morning.
When is a star cluster not a star cluster? When it’s an association. That is when it has begun to dissipate because the gravitational force of the group cannot hold it together. The central stars of the Big Dipper belong to The Ursa Major Association. Below the W shaped constellation of Cassiopeia in the northeast at 9 or 10 p.m. Is the constellation of Perseus (Per-seus or Pers-e-us) as it is usually pronounced. Its brightest star is Mirfak with a designation of Alpha Persei. There are some stars there to the naked eye, but with binoculars there are a great many stars just below naked eye visibility. This is called the Alpha Persei association. It is perfect to spot with binoculars, but way too wide-spread for a telescope.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Constellations Cassiopeia, Perseus and Auriga. Cartes du Ciel
Alpha Persei Association. Created using Stellarium.
11/27/2014 – Ephemeris – The voyage of the Mayflower
Ephemeris for Thanksgiving Day, Thursday, November 27th. The sun will rise at 7:54. It’ll be up for 9 hours and 10 minutes, setting at 5:05. The moon, 2 days before first quarter, will set at 10:51 this evening.
We are regaled with stories of the first Thanksgiving dinner between the Native Americans and the Pilgrims. The Mayflower was headed for the Virginia Colony but were diverted by a storm. Their first landfall in the New World was Newfoundland, where they picked up supplies. Fulling intending to head south to Virginia, the passage became too hazardous, so they put into Cape Cod and there they stayed. Back in those days the ship’s position was determined rather crudely. Latitude was measured by the height of the north star and the sun at noon. Distance and speed were measured with a log thrown overboard with a rope with knots in it. The knots counted over a period of time gave the ship’s speed.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Credit: Scholastic
11/26/2014 – Ephemeris – Where did all the planets go?
Ephemeris for Wednesday, November 26th. The sun will rise at 7:53. It’ll be up for 9 hours and 12 minutes, setting at 5:06. The moon, 3 days before first quarter, will set at 9:41 this evening.
In reviewing which planets are visible tonight, it looks like we’re down to two. Venus, Saturn and Mercury are hanging around near the direction of the Sun. It will be a while before we see them again. However we can see Mars, which will be low in the southwest at 7 p.m. It will set at 8:29 p.m. Mars’ setting time will slowly advance only 6 minutes between now and the end of the year. Jupiter will rise at 10:54 p.m. in the east-northeast. The best telescopic views will have to wait a couple of hours after that. So if you’re more of an early bird rather than a night owl it might be better to view Jupiter with a telescope in the morning. Jupiter has those four bright moons that change position daily, and sometimes while you watch.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Mars with the crescent Moon at 7 p.m. on November 26, 2014. Created using Stellarium.
The crescent moon as it would appear in binoculars at 7 p.m. on November 26, 2014. Created using Stellarium.
Jupiter rising with the winter constellations at 11:30 p.m. on November 26, 2014. Created using Stellarium.
Jupiter with the winter constellations at 6:30 a.m. on November 27, 2014. Created using Stellarium.
Jupiter as seen in a telescope at 6:30 a.m. on November 27, 2014. Created using Stellarium.
11/25/2014 – Ephemeris – Cassiopeia the constellation
Ephemeris for Tuesday, November 25th. The sun will rise at 7:52. It’ll be up for 9 hours and 14 minutes, setting at 5:06. The moon, 3 days past new, will set at 8:33 this evening.
Nearing the zenith at 8 p.m. is the W shaped constellation of Cassiopeia the queen. It’s actually just north of the zenith and since we’re half way from the equator and the north pole at near 45 degrees north, Cassiopeia will not set. Cassiopeia we say is circumpolar. Cassiopeia will rise is set if you’re in Florida. In Antarctica Cassiopeia is a just rumor, just as the Southern Cross is to us in Michigan since it never rises. Cassiopeia lies against the Milky Way, so there are a lot of star clusters in it. Unfortunately they can be seen only in telescopes. In 1572 the last of the pre-telescopic astronomers Tycho Brahe discovered a bright star that suddenly appeared. His discovery broke open the Aristotelian belief that the heavens were changeless.
Times and views are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Looking straight up at the zenith, facing the south, Cassiopeia is just north of the zenith. The lines are radiating from the zenith. where the + sign is. Created using Cartes du Ciel.
My neck hurts just making this chart.
11/24/2014 – Ephemeris – The Summer Triangle is still with us
Ephemeris for Monday, November 24th. The sun will rise at 7:50. It’ll be up for 9 hours and 16 minutes, setting at 5:07. The moon, 2 days past new, will set at 7:29 this evening.
Well it’s almost Thanksgiving and about time that the Summer Triangle of bright summer stars finally set. Except it won’t go just yet. The stars Vega, Altair and Deneb are still hanging around in the west. The bright summer part of the Milky Way is gone. The constellations the three stars are in are Altair in Aquila the Eagle, now flying vertically up, Deneb in Cygnus the swan flying vertically down, and Vega in Lyre the harp, lying on its side. Altair the southernmost of these three will set first, later Vega will also set. What happens to Deneb depends on your location in the Interlochen Public Radio area. It you are north of Traverse City, Deneb will not actually set over Lake Michigan’s northern horizon.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Summer Triangle at 9 p.m. on November 24, 2014. Created using Stellarium.
Vega near its setting point at 11:07 p.m. p.m. on November 24, 2014. Created using Stellarium.
Deneb near its setting point at 5:05 a.m. p.m. on November 25, 2014. Created using Stellarium.
But will Deneb really set for Traverse City. Geometrically it will. However with a flat northern horizon looking northward over the bays to a clean Lake Michigan horizon, atmospheric refraction will bend the light from Deneb making it appear higher in the sky than it really is, so it won’t actually set. On the other side atmospheric extinction, the dimming of stars close to the horizon due to the filtering effect of looking through so much atmosphere would make Deneb impossible to see without a telescope. It might be an interesting challenge to spot.
11/21/2014 – Ephemeris – The Hyades a very important star cluster
Ephemeris for Friday, November 21st. The sun will rise at 7:47. It’ll be up for 9 hours and 22 minutes, setting at 5:09. The moon, 1 day before new, will rise at 7:42 tomorrow morning.
The face of the constellation Taurus the bull looks like the letter V sideways above the rising Orion the Hunter in the east at 9 p.m. The bright star at the tip of a letter V of stars is Aldebaran. Look with binoculars at the letter V shape and you will see the stars of the Hyades star cluster The Hyades is the closest star cluster to us, at about 151 light years. And is important for that reason. Before satellites like Hipparcos. The Hyades were the only star cluster to be directly measured by a technique called parallax, using the radius of the earth’s orbit as one side of a surveyors enormous triangle. Its many stars at the same distance were used to determine distances of star clusters even farther away. Additional techniques based on the distance of the Hyades allow us to measure distances to the galaxies.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Orion and the Hyades.
The Hyades (lower left) and the Pleiades (upper right). My photograph from many years ago.
H-R diagram showing the Hyades and Pleiades. Credit: European Southern Observatory.
The Hertzsprung-Russell diagram or H-R diagram plots stars by brightness on the vertical axis versus surface temperature on the horizontal axis, hot to the left to cool on the right. The plot of stars for open or galactic star clusters, where the stars are burning hydrogen in their cores lie on a diagonal line called the main sequence. When matching the plots of two star clusters based on apparent magnitude the main sequence plot for the more distant star cluster will be dimmer by a certain magnitude difference. Since the brightness of and light source diminishes by the inverse square of the distance. The difference in brightness equates to a difference in distance.
For more information on the H-R diagram check out the Wikipedia article. It’s more than about distance.
