The moon: big, bright, feature-rich but impeached by many astronomers who fight its glare to view the dim light from far-off galaxies. Far from being a celestial nuisance, the Moon is an object worthy of study says John Rowlands, who finds out what its like to become an old (Lunar Phase).
Many people have come up with various pieces of lunar observing software over the years. Lunar Phase Pro is the latest to try and coax our ‘scopes moonward. The single CD-ROM came with no printed instructions, but installation of the 20-Mb pro¬gram was as simple as any other `shove it in the CD drawer and play’ software, and presented no problems. Once up and running, a superbly clear web-style manual is available, containing full instructions, descriptions and graphics of what each screen actually shows.
The general layout of the information on screen is well thought out and tastefully designed in the current trend towards soft, `rounded’ windows graphics. The opening screen presents the current phase of the Moon as seen from your entered latitude and longitude on Earth. Information on the Moon’s age, phase per¬centage, RA and Dec positions, plus apogee and perigee data, are constantly updated in real time alongside the main Moon diagram. A month-to-view calendar with further real-time updated data on the current position, rise and set times of the Moon and Sun occupy separate boxes on the main page, with another box showing the dates-with graphics – of the four principal phases for the month. The phase for each day of an entire month-to-view calendar is selectable under the `Reports’ menu.
Along the top tool bar, the user can select the view as seen through binoculars, telescope with, or telescope without a 90° diagonal. This is a simple but very useful feature that eliminates the need to read lunar maps upside down! The next icon provides a month-to-view screen of rise, transit, and set times for the Moon, together with phase percentage and the start and end times for astronomical, nautical and civil twilight.
The real power of Lunar Phase Pro becomes apparent under the `Reports’ icon. Here, the user can select a variety of graphical and textual information on various aspects. Daily View, for example, shows a very clear, easy-to-understand diagram of the position of the Moon and Sun on the sky, together with their numeric altitude and azimuth positions for each hour of the currently selected day. Allied to this is the Lunar Visibility diagram that graphically represents the phase of the Moon throughout the month using bars of varying thickness traversing a simple day/night background.
Principal lunar features are listed in an extensive tabulated database of over 1600 craters, with separate listings of valleys, sinuses, seas, lakes, and so on taking the total to 1,961 individual features. This includes lunar latitude and longitude, diameter, and a short history on the people and characters immortalised by the naming of a lunar feature. Incredibly, the lunar sunrise and set times are available in tabulated form for every single listed feature – an amazingly useful tool for planning observations of features coming into and out of light. Not surprisingly, this volume of calculation took about 15 seconds on my ageing 400MHz PC, but should not prove too much of a distraction on more recent, faster machines.
The `Reports’ menu is rounded off with basic physi¬cal data on the Moon, equinox dates, and dates of Easter Sunday (though no information was presented for other Moon-dependant religious events such as Ramadan, for example). The lunar eclipse table coped admirably both backwards in time to year 1, and forwards to extremes like 9000AD! Sadly, it is not possible to go back beyond year 1, which could be a useful extension for future releases of the software.
Observing Tool
The so-called `Lunar Explorer’ is the main body of the program and is again very well presented and thoughtfully laid out. Three user-selectable graphics resolu¬tions provide from good to near-photographic detail of both the near and far sides of the Moon. A crosshair cursor shows current latitude and longitude, and a click on a particular feature identifies the name, size, historical information and sunrise/sunset data. Lunar latitude and longitude grids can be overlaid on the maps if required.
Perhaps the most heavily used tool will be the `find-a-feature’ capability. All databases can be displayed alongside the main map, and a click on any of the listed features will highlight it with a yellow ring. Another useful tool is the table of features currently lying along the terminator.
Extensive comparison against the Royal Astronomical Society’s authoritative Moon maps in The Atlas of the Solar System showed the mapping to be accurate and feature identification reliable. There is a variable `zoom’ feature and the programme allows a full disk or quadrant view in spherical and mercator projections, though I found spherical provides much better feature resolution. Polar plots are also available. Some craters down to about 13km in diameter could be resolved by the feature identification on the near side map, but typically only to about 40km on the far side.
A beautiful feature of the program is the animation of the Moon through the month. This shows the changing phases, plus the quite considerable effects of libration – principally due to the elliptical nature of the orbit – as the Moon oscillates in latitude and longitude as seen from the Earth. In total, this allows 59% of the Moon to be visible from Earth.
Lunar Phase Pro is completed with the ability to print out quality maps and tables as displayed on-screen, and a menu of web-based resources for further Moon observing and exploration information.
Back to the Moon?
Does Lunar Phase Pro offer anything more than a good Moon-observer’s book and paper maps provide? Well, if you want every last piece of up-to-the-second data on the Moon, and want to plan your observing sessions in advance then yes, the software will give you everything you need to know and more. If you’re new to astronomy or, like me, more of a casual Moon observer, then the powerful database linked to feature finding and identification will prove much more convenient than trawling through paper maps under low light. In comparison to other Moon observing software I’ve seen, Lunar Phase Pro is streets ahead.
The program is now in revision 1.50. In future releases it may want to include more database detail to satisfy the most serious of lunar observers. As it stands, it’s excellent value for money and perfectly suited to beginners and those whose main observing activity lies beyond the Moon.
– Astronomy Now Magazine
Filed under: Astronomy Software
What is the phase of the moon today?
Astronomers use the right ascension and declination system which can be compared to the latitude and longitude system on the earth's surface. This system is defined on the "celestial sphere" which is the two dimensional projection of the sky on the sphere around the earth. In this system the zero point of the declination is the "celestial equator" which is parallel to the earth's equator. So, in other words, if you were standing at a spot on the equator you would "see" the celestial equator as an arc passing directly overhead. The declination is 0degrees for a source on the celestial equator and is 90degrees for a source at the north pole. Sources below the equator would have negative declinations. The zero point of the right ascension is the vernal equinox which is the point at which the sun moves into the northern celestial sphere and marks the position of the sun on the first day of spring. The right ascension increases to the east and is measured in units of time.
The phase of the moon has to do with the moon, not you. Now, whether it's day or night for you or for me (in the US), depends on the orientation of the earth and the sun. We also get into the discussion of whether it's precisely, to the second , a FULL moon, or whether it's a couple of days on either side of full, which most people , especially in the newspaper, would CALL a 'full' moon.
This last little item , when to call it full, is the problem with the myth of 'more accidents and crazy people in ER's and so on' at the 'full' moon….fact is, people tend to 'stretch' the time of the full moon particularly to suit their needs.