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03/31/2015 – Ephemeris – Previewing April skies
Ephemeris for Tuesday, March 31st. The Sun will rise at 7:25. It’ll be up for 12 hours and 42 minutes, setting at 8:08. The Moon, half way from first quarter to full, will set at 6:02 tomorrow morning.
The 4th month of the year begins tomorrow. Daylight hours in the Interlochen/Traverse City area and will increase from 12 hours and 45 minutes tomorrow to 14 hours 11 minutes on the 30th. The altitude, or angle, of the sun above the southern horizon at local noon will be 50 degrees tomorrow and will ascend to 60 degrees on the 30th. The altitude of the Sun in the Straits area will be a degree lower. The actual time of local apparent noon this month for the Interlochen/Traverse City area, when the sun passes due south, will be about 1:43 p.m. For the straits area local noon occurs about 4 minutes earlier. This Saturday morning we’ll see the first part of a lunar eclipse. This month Venus and Jupiter are our evening planets.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Star Chart for April 2015. Created using my LookingUp program.
The Moon is not plotted. The planets and stars are plotted for the 15th at 10 p.m. EDT. That is chart time.
Evening Astronomical twilight ends at 9:51 p.m. EDT on April 1st, increasing to 10:42 p.m. EDT on the 30th.
Morning astronomical twilight starts at 5:43 a.m. EDT on April 1st, and decreasing to 4:41 a.m. EDT on the 30th.
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.
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.
- Drill a hole in the bowl of the Big Dipper and the water will drip on the back of Leo the Lion.
- Follow the arc of the Big Dipper’s handle to Arcturus
- Continue with a spike to Spica
Calendar of Planetary Events
Credit: Sky Events Calendar by Fred Espenak and Sumit Dutta (NASA’s GSFC)
To generate your own calendar go to http://eclipse.gsfc.nasa.gov/SKYCAL/SKYCAL.html
Times are Eastern Daylight Time on a 24 hour clock. Some additions made to aid clarity.
Conjunctions like the Moon-Saturn: 2.3° S means Saturn will appear 2.3° south of the Moon.
| Apr | 01 | We | Venus: 36.6° E | |
| 01 | We | 08:59 | Moon Apogee: 406000 km | |
| 03 | Fr | 23:17 | Moon Ascending Node | |
| 04 | Sa | 08:01 | Partial Lunar Eclipse* | |
| 04 | Sa | 08:06 | Full Moon | |
| 06 | Mo | 09:48 | Uranus Conjunction | |
| 08 | We | 09:08 | Moon-Saturn: 2.3° S | |
| 08 | We | 10:16 | Jupiter-Beehive: 5.4° S | |
| 09 | Th | 23:52 | Mercury Superior Conj. | |
| 10 | Fr | 03:46 | Moon South Dec.: 18.2° S | |
| 11 | Sa | 11:30 | Venus-Pleiades: 2.6° S | |
| 11 | Sa | 23:44 | Last Quarter | |
| 16 | Th | 23:53 | Moon Perigee: 361000 km | |
| 17 | Fr | 09:07 | Moon Descending Node | |
| 18 | Sa | 14:57 | New Moon | |
| 21 | Tu | 12:35 | Moon-Aldebaran: 0.9° S | |
| 21 | Tu | 14:09 | Moon-Venus: 6.8° N | |
| 22 | We | 19:21 | Lyrid Shower: ZHR = 20 | |
| 22 | We | 19:26 | Moon North Dec.: 18.3° N | |
| 25 | Sa | 19:55 | First Quarter | |
| 28 | Tu | 23:55 | Moon Apogee: 405100 km | |
| 30 | Th | 21:29 | Mercury-Pleiades: 1.7° S | |
* For the Grand Traverse area the partial phase of the eclipse will begin at 6:15 a.m. The eclipse will be interrupted by the moon setting at 7:24 a.m. Sunrise will occur at 7:17 a.m. More information will be provided in the Thursday, April 2nd post.
03/30/2015 – Ephemeris – The importance of meteorites and asteroids
Ephemeris for Monday, March 30th. The Sun will rise at 7:27. It’ll be up for 12 hours and 39 minutes, setting at 8:07. The Moon, 3 days past first quarter, will set at 5:33 tomorrow morning.
On Friday the 3rd Joe Brooks will be giving a talk at the Grand Traverse Astronomical Society on meteorites. That will be at 8 p.m. at Northwestern Michigan College’s Rogers Observatory. NASA has the Dawn spacecraft now settling into orbit of the largest asteroid Ceres. It is the asteroid belt that is the source of meteorites. Meteorites are either pieces of destroyed protoplanets due to collisions in the asteroid belt or primitive objects like carbonaceous chondrites pristine that date back to 4.567 billion years ago, the formation of the solar system. Meteorites tend to be contaminated by the environment. That’s why samples of asteroids will be so valuable for planetary defense and understanding the origin of the solar system.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Looking back at Vesta as Dawn headed off to Ceres. Credit: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA
The bright spot is two. Picture taken February 19, 2015 from 29,000 miles (46,700 km). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.
03/27/2015 – Ephemeris – The North Star, Polaris
Ephemeris for Friday, March 27th. The Sun will rise at 7:33. It’ll be up for 12 hours and 30 minutes, setting at 8:03. The Moon, at first quarter today, will set at 3:49 tomorrow morning.
Tonight we turn our eyes northward to Polaris, the North Star. It is the closest bright star to the north pole of the sky. It appears nearly stationary as all the other stars appear to revolve around it as the Earth rotates. Some folks, think that Polaris is the brightest star in the sky. It’s not. It is a good solid second magnitude star, about the brightness of a Big Dipper star. The Big Dipper can be used to point to it, by using the two stars at the front of the bowl. Polaris is at the end of the handle of the Little Dipper. The Little Dipper has four dim stars in its rather oddly bent handle and back of its bowl. The two stars at the front of the bowl of the Little Dipper are Kochab and the dimmer Pherkad, which are also called the Guard Stars or the Guardians of the Pole.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
How to find Polaris. The grid is the equatorial grid showing the proximity to the pole. Created using Stellarium.
03/26/2015 – Ephemeris – Regulus the 21st brightest of the 21 brightest “First Magnitude” stars
Ephemeris for Thursday, March 26th. The Sun will rise at 7:35. It’ll be up for 12 hours and 27 minutes, setting at 8:02. The Moon, 1 day before first quarter, will set at 3:04 tomorrow morning.
The bright star below and left of Jupiter as it shines in the southeast in the evening is the star Regulus in Leo the lion. It’s at the base of the backward question mark of stars that make up the head and mane of Leo. It is also an asterism or informal constellation of the Sickle. Regulus is the dimmest of the 21 brightest stars which are called First Magnitude Stars. It is a quadruple star system with two pairs of stars. Regulus is a blue-white star which is rapidly spinning with a period of something like 16 hours, orbited by a possible white dwarf star every 40 days. The star system is 79 light years away. The name Regulus translates to something like Little King Star, befitting its location in the King of the beasts.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Leo, Regulus and nearby constellations as seen in the east-southeast at 9 p.m. March 26, 2015. Created using Cartes du Ceil (Sky Charts).
Below, zooming in to Regulus BC, the second pair of stars of the Regulus system, which is about 3 minutes of arc northwest of Regulus. It consists of an 8th magnitude and a 14th magnitude star with the same proper motion (motion against the sky) as Regulus.
The star TYC 833-134-1 is Regulus B, which is easily visible in telescopes at magnitude 8.1. The star is also listed as HD 87844. The first designation is from the Tycho catalog and is how it’s referenced in Cartes du Ceil. The star is shown, but not named in Stellarium. The is equatorial orientation is created using Cartes du Ceil (Sky Charts).
03/25/2015 – Ephemeris – Where are the bright planets tonight?
Ephemeris for Wednesday, March 25th. The Sun will rise at 7:37. It’ll be up for 12 hours and 24 minutes, setting at 8:01. The Moon, 2 days before first quarter, will set at 2:13 tomorrow morning.
Lets take a look at the bright planets for this week. Brilliant Venus is in the west by 8:30 p.m. It will set at 11:07 p.m. Mars appears much lower and to the right of it. The Red Planet will set tonight at 9:48. Jupiter will appear In the southeastern sky in the evening. It will set at 5:48 a.m. It’s near the sickle-shaped head of Leo the lion, and it’s the second brightest star-like object in the sky after Venus. In telescopes tomorrow morning the moon Io will duck behind Jupiter at 1:05, but will pop into sunlight a bit away from the planet on the other side at 4:23 a.m. because it also will be hidden in Jupiter’s shadow. Early risers will be able to spot Saturn which will rise in the east-southeast at 12:59 a.m. It will be low in the south at 6 to 7 a.m.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The evening planets of Mars, Venus and Jupiter with the Moon and winter stars. Created using Stellarium.
The Moon as it would appear in binoculars at 9 p.m. March 25, 2015. Created using Stellarium.
Jupiter and its moons at 9 p.m. March 25, 2015. Created using Stellarium.
Saturn and the southern summer constellations at 6 a.m. on March 26, 2015. Created using Stellarium.
What Saturn and its moons might appear like in a telescope at 6 a.m., March 26, 2015. Small telescopes will show only the moon Titan. Created using Stellarium.
03/24/2015 – Ephemeris – The Moon will be passing in front of the Hyades tonight
Ephemeris for Tuesday, March 24th. The Sun will rise at 7:38. It’ll be up for 12 hours and 21 minutes, setting at 8:00. The Moon, 3 days before first quarter, will set at 1:16 tomorrow morning.
Tonight he Moon will be crossing in front of the Hyades star cluster, otherwise known as the face of the constellation Taurus the bull. The Moon will make it about half way across by the time it sets. The Moon is 2160 miles in diameter and moves about the same distance in an hour as it orbits the Earth. The International Space Station and other satellites in low Earth orbit have to travel 17,500 miles an hour to stay in orbit. But since the Earth’s gravity, or the gravitational force of any body diminishes with the square of the distance. Double the distance and the gravitational force diminishes by a factor of four. This inverse square law as it is known also works with the diminution of light with distance from its source.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Moon is travelling in front of the Hyades at 10 p.m. March 24, 2015. Created using Stellarium.
03/23/2015 – Ephemeris – Olbers’ Paradox or why it’s dark at night
Ephemeris for Monday, March 23rd. The Sun will rise at 7:40. It’ll be up for 12 hours and 17 minutes, setting at 7:58. The Moon, 3 days past new, will set at 12:12 tomorrow morning.
Why is it dark at night? It seems like a dumb question but it isn’t, or wasn’t when the question was first asked by Henrich Wilhelm Olbers who lived from 1768 to 1840. The dark sky problem is called Olbers’ Paradox. If the universe was uniformly filled with stars and infinite in size all the stars would overlap giving a bright sky, day or night. The fact that it doesn’t tells us something about the universe. Stars are not uniformly scattered throughout the universe, they are bound up into galaxies, also the more distant stars in their galaxies are red shifted, losing energy. Also if the universe is really infinite, parts of it are receding faster than the speed of light, so we can’t see them. Receding faster than light, how can that be? Though matter cannot move faster than light, space can expand faster than light.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
“Olbers’ Paradox – All Points.” Credit: Kmarinas86, Licensed under CC BY-SA 3.0 via Wikimedia Commons
03/20/2015 – Ephemeris – Spring will spring forth at 6:44 p.m. EDT
Ephemeris for Friday, March 20th. The Sun will rise at 7:46. It’ll be up for 12 hours and 8 minutes, setting at 7:55. The Moon is new today, and won’t be visible.
The Arctic solar eclipse has just ended. But there is one more event of note today. At 6:44 p.m. The Sun will cross the celestial equator heading northward, the projection of the Earth’s equator on the sky. In doing that the season of spring will return to the northern hemisphere. The Sun is already staying up for just over half the day. That will increase to fifteen and a half hours by the summer solstice three months from now. Not only will the Sun will be out longer, but it will rise higher in the sky, rising from 45 degrees altitude in the south at local noon to 69 degrees on June 21st. If the sun stayed at this location it would get very uncomfortable with the heat. As it is as the Sun is climbing down it will still get warmer. Peak summer heat occurs about a month after the solstice.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
These are whole sky diagrams with the edge at the horizon. The Sun’s motion is from left to right. The Sun is plotted every 15 minutes. The Sun’s motion is constant, however the projection causes squeezing of the positions near the zenith (center of the diagram) and stretching near the horizon.
The sun’s daily path through the sky from horizon to horizon on an equinox the first day of spring or autumn. Credit My LookingUp program.
The sun’s daily path through the sky from horizon to horizon on the first day of summer, the summer solstice. Credit My LookingUp program.
03/19/2015 – Ephemeris – A remarkable solar eclipse tomorrow, however we, in the US, won’t see it.
Ephemeris for Thursday, March 19th. The Sun will rise at 7:48. It’ll be up for 12 hours and 5 minutes, setting at 7:53. The Moon, 1 day before new, will rise at 7:50 tomorrow morning.
There will be a rare solar eclipse tomorrow. The bad news is that it won’t be visible from here. Be that as it may, it is total for a circle of ocean near Greenland, and because tomorrow is also the vernal equinox the it is also sunrise at the north pole. As it happens the path of the eclipses totality tracks to the north pole, so the eclipse, partial and total will be visible from there. I’m not sure how long it’s been since an eclipse totality was visible at the pole on an equinox. The next solar eclipse visible from the United States will be on August 21, 2017. This is an eclipse, whose path of totality crosses the continental United States. In about 2 weeks we’ll have a lunar eclipse whose first stages can be seen from northern Michigan in morning twilight.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Pertinent section of the March 20, 2015 total solar Eclipse map. Click on image above for the entire image. Credit: Fred Espenak, NASA’s GSFC.
03/18/2015 Ephemeris – It’s Wednesday, so where are all the bright planets?
Ephemeris for Wednesday, March 18th. The Sun will rise at 7:50. It’ll be up for 12 hours and 2 minutes, setting at 7:52. The Moon, 2 days before new, will rise at 7:14 tomorrow morning.
Lets take a look at the bright planets for this week. Brilliant Venus is in the west by 8:30 p.m. It will set at 10:49 p.m. Mars appears below and right of it. The Red Planet will set tonight at 9:47. Jupiter will appear In the southeastern sky in the evening. It will set at 6:41 a.m. It’s near the sickle-shaped head of Leo the lion, and it’s the brightest star-like object in the sky after Venus sets. In telescopes tonight the moon Io will duck behind Jupiter at 11:17, but will pop into sunlight a bit away from the planet on the other side at 2:28 a.m. because it also will be hidden in Jupiter’s shadow. Early risers will be able to spot Saturn which will rise in the east-southeast at 1:27 a.m. It will be low in the south at 6 to 7 a.m.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Jupiter, Venus and Mars at 9 p.m. March 18, 2015. Created using Stellarium.
Saturn and the summer constellations of Scorpius and Sagittarius at 6:30 a.m. March 19, 2015. Created using Stellarium.
Planets to the same scale as viewed in a telescope of the same power. Venus and Jupiter at 8:30 p.m. on March 18, 2015. Saturn at 6:30 a.m. on March 19. 2015. Created using Cartes du Ceil (Sky Charts).
Bob Moler's Ephemeris Blog 