Archive
08/21/2012 – Ephemeris – The moon, the planets Mars, Saturn and the star Spica get together tonight
Ephemeris for Tuesday, August 21st. The sun rises at 6:52. It’ll be up for 13 hours and 44 minutes, setting at 8:37. The moon, 3 days before first quarter, will set at 10:21 this evening.
Tonight the moon will join the triangle of the planets Saturn, Mars and the star Spica. Mars is the dimmest of the three star-like objects and is nearly directly above the moon. Saturn is yellowish and to the upper right, while the star Spica is the bluest of the 21 brightest first magnitude stars. Mars gets its color from rust, good old iron oxide. Saturn has a yellowish tinge due partly to the color of its cloud tops. The color of the rings is much more white of ice. But since Saturn reflects the sun, some of that yellowness come from the sun itself. While the daylight sun appears white to us, our night vision shifts to the blue, so sunlike stars appear yellowish. This shift to the blue also enhances the color of a blue star like Spica.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The moon and the planets Mars and Saturn plus the bright star Spica before 10 p.m. Created using Stellarium.
Spica is the unnamed star to the right of the moon.
07/26/2012 – Ephemeris – Why is a half illuminated moon called a quarter moon?
Ephemeris for Thursday, July 26th. The sun rises at 6:22. It’ll be up for 14 hours and 51 minutes, setting at 9:14. The moon, at first quarter today, will set at 12:56 tomorrow morning.
The moon was at the exact first quarter a few hours ago. By tonight the sunlit side of the moon will be a bit fuller, but might be at the half moon phase to the casual eye. So why do we call the half illuminated moon a quarter moon? The moon is a quarter the way around the earth from new moon. When it goes half way around the earth from new, we ave a fully illuminated moon from our vantage point, Another quarter the way around we have a half illuminated moon from our vantage point, but the moon is at third quarter position or last quarter. Another quarter way around and the moon is new again. The ancients unlike astronomers today called the first sighting of the moon’s crescent in the west after sunset new moon.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Lunar phase diagram. From Wikimedia Commons.
The arrows in the diagram is light from the sun far off to the distant right.
07/13/2012 – Ephemeris – The moon will join Venus and Jupiter Sunday morning
Ephemeris for Friday, July 13th. Today the sun will be up for 15 hours and 15 minutes, setting at 9:25. The moon, 3 days past last quarter, will rise at 2:26 tomorrow morning. Tomorrow the sun will rise at 6:11.
Sunday Morning maybe isn’t the most convenient time to get up early, but this Sunday it may be worth it. At 5 a.m. or so Jupiter will appear above Venus, as they have for the last few weeks. But Sunday morning the crescent moon will appear right between the two. For other parts of the world the moon will actually pass in front of Jupiter, an event called an occultation. This will occur before sunrise for us. But still the planet and moon group should be a beautiful sight in the twilit sky. Venus and Jupiter will soon separate, Venus to stay near the sun, while Jupiter due to the earth’s orbital motion moves away to rise earlier and earlier by somewhat less than a half hour a week. Jupiter lies in the constellation Taurus now.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Jupiter, Venus and the moon on July 15, 2012 at 5 a,m, Created using Stellarium.
05/29/2012 – Ephemeris – The moon tonight
Ephemeris for Tuesday, May 29th. Today the sun will be up for 15 hours and 16 minutes, setting at 9:18. The moon, 1 day past first quarter, will set at 2:38 tomorrow morning. Tomorrow the sun will rise at 6:01.
The moon tonight is a wonderful sight for binoculars or a small telescope. There are some very nice craters now revealed near the terminator, the line between day and night on the moon. The terminator in the two weeks between new and full is the sunrise line on the moon. From the top or north on the moon is the flat floored crater Plato Then about midway down the moon and right on the terminator is the beautiful crater Copernicus. Then to the south end of the moon is the bright and crisp crater Tycho. Its splash marks called rays will be better revealed at full moon. At the bottom of the moon, just coming into light is the huge crater Clavius. A telescope will reveal smaller craters within.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The moon on 5/29/2012 showing large craters on the terminator. Created using Virtual Moon Atlas.
05/24/2012 – Ephemeris – Phases and shadows on the moon
Ephemeris for Thursday, May 24th. Today the sun will be up for 15 hours and 8 minutes, setting at 9:13. The moon, half way from new to first quarter, will set at 12:11 tomorrow morning. Tomorrow the sun will rise at 6:04.
The fat crescent moon tonight is like the crescent Venus, with the sun shining on mostly the far side. I notice that some folks think that the earth is casting its shadow on the moon to cause the crescent. That isn’t correct. The earth does cast its shadow on the moon sometimes, but only at full moon, but only about one in 6 full moons, and we usually don’t see many of these. The phases of the moon are simply the light and shadow of a ball in the sunlight. In fact, if before sunset you can see the moon, and you are in sunlight also. Hold the ball up next to the moon. You will see that the ball will have the same phase as the moon. This is because the moon is close to the earth.
05/22/2012 – Ephemeris – The moon appears near Venus tonight
Ephemeris for Tuesday, May 22nd. Today the sun will be up for 15 hours and 4 minutes, setting at 9:11. The moon, 2 days past new, will set at 10:50 this evening. Tomorrow the sun will rise at 6:06.
Tonight the extremely thin crescent moon will appear below and left of the planet Venus. Venus itself is an extremely thin crescent, just two weeks from passing directly in front of the sun in a rare transit part of which will be visible from here. Venus is a crescent because we are looking mostly on its night side, with just a sliver of light on its sunlit edge. Even though Venus shows such a small sunlit sliver, it’s still very bright, since its nearness to us makes it appear larger in our sky. You can even see the crescent in binoculars. Venus is so bright because it’s close to us, just slightly smaller than the earth, but socked in by while sulfuric acid clouds that reflect most of the suns light covering a runaway green house effect beneath.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Venus with the moon on the evening of May 22, 2012. Created using Stellarium.
04/24/2012 – Ephemeris – The moon appears near Venus tonight
Ephemeris for Tuesday, April 24th. The sun rises at 6:42. It’ll be up for 13 hours and 56 minutes, setting at 8:39. The moon, 3 days past new, will set at 12:05 tomorrow morning.
This evening the moon will appear near Venus with the brilliant planet above and right of the moon. The moon should still exhibit earthshine. On the 30th Venus will attain its greatest brightness of -4.6 magnitude. Only the moon and sun are brighter. In a telescope Venus has a crescent phase and as you view Venus for the next month its phase will get thinner and its size gets larger. This is as it approaches us as it moved more closely between us and the sun. It’s quite a show to watch for. Folks with a low western horizon and clear skies should be able to follow Venus to within a few days of its transit across the face of the sun. Then in bright twilight Venus will have the thinnest of crescents, and appear larger than Jupiter.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Venus and the moon at 9 p.m. April 24, 2012. Created using Stellarium.
04/23/2012 – Ephemeris – The moon will appear near the Pleiades tonight
Ephemeris for Monday, April 23rd. The sun rises at 6:44. It’ll be up for 13 hours and 53 minutes, setting at 8:37. The moon, 2 days past new, will set at 11:13 this evening.
This evening the thin crescent moon will appear near the Pleiades, or Seven Sisters. They will appear just to the right of the thin sliver of the moon. If you look closely at the moon the entire Moon will be visible. That’s because the nearly full Earth is shining on it. The phase of the earth in the moon’s sky is exactly the opposite of the moon’s phase in the earth’s sky. The effect is called earth shine and was first explained by Leonardo DaVinci. For future astronauts spending a two week night on the moon’s near side, the full earth in its skies will be much brighter than the full moon looks in our skies. The earth covers 16 times the sky as the moon and is more than twice as reflective as the moon. The moon will continue to move eastward and will be near Venus tomorrow.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The moon and the Pleiades on April 23rd at 10 p.m. Created using Stellarium.
Note that Stellarium shows a photograph for the Pleiades. The blue reflection nebula is not visible to the eye, and the stars of the Pleiades aren’t that bright in comparison to the moon.
03/29/2012 – Ephemeris – The moon tonight
Ephemeris for Thursday, March 29th. The sun will rise at 7:28. It’ll be up for 12 hours and 38 minutes, setting at 8:06. The moon, 1 day before first quarter, will set at 2:55 tomorrow morning.
Tonight’s moon will be nearly half full. The gray patches on the moon are from the upper right the sea of Crises, Below it is the sea of fertility, centered on the moon’s equator is the sea of Tranquility. Above that is the scallop shaped sea of Serenity. One of the interesting craters in viwe for a telescope now is the ruined crater Julius Caesar. It’s on the edge of Tranquility near Serenity. This is an ancient crater whose crater walls were breached by the impact that created the sea of Tranquility, so it kind of looks like the letter C. So how did this crater become named for a Roman Emperor? My only guess is that it was for his calendar reform giving us the 365 day year with a leap year every 4th. This is also a good time to check out the rest of the moon.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The moon at 10 p.m. 3/29/2012. Created using Virtual Moon Atlas.
03/26/2012 – Ephemeris – The moon will pass Venus today
Ephemeris for Monday, March 26th. The sun will rise at 7:33. It’ll be up for 12 hours and 29 minutes, setting at 8:03. The moon, half way from new to first quarter, will set at 12:25 tomorrow morning.
Yesterday the moon moved past Jupiter in the sky. Today the moon will pass Venus, the brightest planet. Check them out in the west southwest in the evening after sunset. Venus is going to be at greatest elongation from the sun tomorrow. Venus is at an angle of 46 degrees from the sun, and it will soon diminish. As it does, this is the best time to view Venus in a telescope. 400 years ago Galileo observed Venus with his small telescope and observed that Venus had phases like the moon, and its size changed proving that Venus orbited the sun and not the earth. You can repeat his observations this spring. Venus now appears about half illuminated by the sun, like the quarter moon. Its phase will thin and it will grow in size.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Moon passing Venus with Jupiter below. Created using Stellarium.
Bob Moler's Ephemeris Blog 