Here are some of the questions which visitors to Inconstant Moon have asked. They have been divided into six sections...
|movement:||the moon's orbit and phases|
|physical:||form, characteristics and geology|
|phenomena:||unusual lunar events|
|observation:||what can be seen... and what can't|
|terminology:||naming of the moon, phases and features|
|miscellaneous:||anything not covered avove|
If you cannot find the answer to your question, go ahead and ask it!
In a surprise request, my 8 year old daughter said she wanted a telescope for Christmas. A week or so later, in September, we experienced a very clear night on or near the full moon. I let the girls, 8 and 6 years old, look at the moon with a pair of auto-focus binoculars. It was not really that great of a view, but they got so "psyched" I had trouble getting them to fall asleep. Could you suggest what to look for in an appropriate first telescope that would keep in mind the family budget?
a: An excellent question - there are some traps out there for the newcomer, and it's very easy to buy the wrong instrument, have a disappointing experience and give up on astronomy altogether. With a little care, though, your daughters could be inspired to follow an interest which can last a whole lifetime!
A good beginner's telescope would be a simple, lightweight one with a good field of view and good quality optics. Decent telescopes start at around $250. If this is more than you want to pay, seriously consider getting a good pair of binoculars. You'll get much better results with a well-chosen pair of high quality binoculars than a "more powerful" telescope with poor optics.
Here is the most useful single piece of advice I can give: do not judge a telescope by its magnifying power. You will sometimes see small telescopes sold on the strength of enormous magnification. This is almost always a bad sign. The two things you really need from a telescope are the ability to collect lots of light and the ability to produce a detailed image. The key to both of these is aperture, ie having a decent-sized main lens or mirror (called the primary). Any telescope could have a million-times-magnification eyepiece attached, but without enough aperture the small amount of light collected would be diluted to the point of invisibility (for the same reason that even the very best torch could never light up a whole football field).
These are your basic choices -
The market leaders for telescopes are Meade and Celestron. Both produce excellent instruments. Astronomy magazine carries advertising from many reputable manufacturers and suppliers, and plenty of articles appropriate to a family starting in astronomy.
One final plea. If you buy a telescope from a responsible manufacturer this will not arise, but if the instrument you buy has a solar filter which fits to the eyepiece, THROW IT AWAY. Even with the aperture reduced, the glass in these filters becomes very hot and can explode, leaving the eye exposed to a powerful, focussed beam of sunlight. The consequences do not bear thinking about.
Can you explain Universal Time and how I calculate it in relation to the South of England?
(Jody, Salisbury, UK)
a: Universal Time (UT) is what astronomers use when they describe events which happen simultaneously for all observers. For instance, anyone watching a lunar eclipse will see the Earth's shadow appear on the Moon at the same moment, wherever they are in the world. An astronomer might say that the total phase of the eclipse will begin at 15:23 UT or perhaps 15h 23.0m UT.
On the other hand, in an occultation the Moon may appear to pass in front of a star or planet at a range of different times depending on your location. These will often be expressed in local time.
UT is sometimes called Universal Time Co-ordinated or UTC. It has no time zones and it doesn't change during the summer. Observers in the UK are lucky: UT is the same as Greenwich Mean Time (GMT) and one hour different from British Summer Time (BST), so during the winter you don't need to change it and during the summer UT = BST - 1h.
q: In the film 2001: A Space Odyssey, in the crater Tycho was buried the Monolith which is activated by the sun. According to a friend of mine if one were to follow the "timeline" in 2001, on Thursday 26th April was the date the Monolith transmitted a signal.
I informed him that his "data" is incorrect, as the sun doesn't get close to Tycho until the 30th of April. Assuming the Monolith was buried in the centre of Tycho, what time would sunlight strike the Monolith?
(John Goerger, Orange Ca)
a: You would both appear to be correct! This quote from an early script for the film would tie in with your friend's timeline: "The first surface was exposed at 0843 on
These are not the only technical faults with 2001. In the relevant scene (shown here courtesy of MGM/UA) the Earth is seen in the lunar sky. It is far too close to the horizon, incorrectly suggesting that Tycho is close to the lunar pole. More relevantly, the Earth shows a gibbous phase. Sunrise at Tycho happens when the Moon seen from Earth is at gibbous phase, in which case the Earth seen from the Moon will be at crescent phase.
When leaving the surface of the Moon, Neil Armstrong said goodnight to someone (ie "goodnight Mr Gurski"). What did he say, and why did he say it?
(Fred Kolthay, Mahopac, NY)
a: A story has been circulating for some years on the Internet relating to the comment "Good luck, Mr Gorski" spoken by Neil Armstrong at the end of his first moonwalk. The meaning of these cryptic words is clever, risque and funny (and unfortunately cannot be explained on a family site). The only thing which detracts from it is that it never happened, as the mission transcripts reveal.
Is it true that some people have paid to have a holiday on the Moon (some day)?
a: It seems unlikely that any bookings have been taken, as timescales and prices are an unknown quantity, but several large hotel and catering (including Hilton, Sheraton and McDonalds) have begun making serious plans. Architects have devised innovative construction techniques, and food technologists have been working on new methods to grow, manufacture and cook food. The greatest limiting factor is the exorbitant cost of transporting each pound of material from the Earth. Any long-term lunar population needs to be largely self-sufficient.
the moon an artefact?
Has it ever occurred to you that the Moon was put in place by aliens? The Moon doesn't rotate, very unusual. It is the exact distance from the Earth to obscure the Sun during eclipses. It seems to be hollow as the result of seismic testing by our astronauts. Bright lights and unusual structures have been seen on the Moon since there have been telescopes. Finally, the Earth and Moon are different composition and ages, the Moon isn't part of the Earth.
(Tom Anger, Houston)
a: There is a scientific/philosophical principle called Occam's Razor which says, in essence, that when seeking an explanation you should not make any more assumptions than are necessary . Bearing that in mind, consider the points one at a time...