EDUCATION ORDERS 1-877-290-8256
EDUCATION ORDERS 1-877-290-8256
 |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
For education orders please call 1-877-290-8256. Welcome again to our monthly newsletter with features on exciting celestial events, product reviews, tips & tricks, and a monthly sky calendar. We hope you enjoy it!
One of things I find myself doing in my astronomy outreach activities is answering a lot of questions. I use a variety of resources in my answers, such as the Royal Astronomical Society of Canada's Observer's Handbook, W. H. Finlay's Concise Catalog of Deep-Sky Objects (Springer), and Wikipedia, whose astronomical content is remarkably thorough and accurate. But, most of all, I use Starry Night. Identifying UFOs UFOs are, by definition, Unidentified Flying Objects. Usually these are reported by people unfamiliar with the normal appearance of the sky, and turn out to be perfectly ordinary astronomical objects. Starry Night is an excellent tool for identifying the unidentified. I set the location to the observer's location, the time and date to the reported time and date of the incident, and then use Starry Night to look in the direction the object was reported. Nine times out of ten this turns out to be either a planet or a bright star. Sometimes the description helps narrow things down. A “blinking” object is usually a twinkling star, as opposed to the steady light of a planet. Many “eye-witness” descriptions are highly inaccurate. Many people seem to have no idea what the cardinal compass directions are in their locality. Some rely on street names with north-south or east-west in them, unaware that these directions are often way off from actual compass directions. I've known about this for a long time, having grown up in Montreal, where the conventional street grid is rotated almost 90° from the true compass directions. The “east-west” streets, like Sherbrooke Street, run almost north-south. Google Maps is often very useful for checking on this. People often report odd or erratic motion, particularly with objects which are probably artificial satellites. A point source (satellite) moving with absolute smoothness and regularity against a background of point sources (stars) is often reported as zigzagging—this is a well-known optical illusion. The Moon is frequently reported as being unusually large, usually when low on the horizon. This is the well known (but somewhat mysterious) “Moon Illusion.” Although the Moon never changes size as the Earth rotates beneath it, this illusion is so commonplace that Starry Night shows the Moon as much larger than it really is, in order to replicate this illusion (right-click on the Moon and select Enlarge Moon). Current Events I often get questions about “current events” in the sky. These include upcoming or recently past lunar phases, eclipses, and conjunctions. All recent versions of Starry Night include a SkyCal tab, which opens a pane showing the current month's calendar (with navigation buttons to reach other months and years), a “Browser” which shows calendars downloaded monthly from the Starry Night web site as part of data updates, and “Info” about particular events from the two sections above.
A word about the monthly calendars. I prepare these each month myself. They display most events from the perspective of the Earth's center rather than particular localities, though sometimes they are set up for particular locations on Earth, especially for eclipses. So, in most cases, you will need to shift the observing location to your own location. Beginning with version 6.0 of Starry Night, this feature is gradually being replaced by the interactive “Events” tab and pane, which uses Starry Nights own internal functions to detect many classes of events for any period in the past and future. Want to know what's really going to happen in 2012? Set the date range from January 1 to December 31, and “Events” will tell you. No apocalypse or Armageddon? Sorry but Starry Night doesn't predict such things! General Information Starry Night can answer a tremendous variety of information about astronomical objects and events. Left-click (Windows) or command-click (Mac) on any object to get its contextual menu, and you will see the options “Online Info...” and “Show Info.” “Online Info...” looks up the object in Wikipedia in your browser, and “Show Info” displays the information about the object contained within Starry Night itself. Among other things, the “Info” pane gives you the times of rising, transit and setting for the current date at the current location. It gives you a short description of the object, its position in the sky, position in three dimensional space, and a variety of other data depending on the kind of object it is. Specific Questions A few weeks ago, I was asked about past and future pole stars. While Starry Night displayed the effects of precession accurately, it was a tedious process to advance in time and then check where the poles were located. Within a day or two of my being asked this question, the update to Starry Night 6.4 was released, and suddenly the answer became really easy. Starry Night 6.4 now includes precession “clocks” for both hemispheres. They can be turned on in the “Options” pane under Guides:Celestial Guides: Pole Precession Circles.
Lately there have been a lot of reports, especially on YouTube, about strange and erratic behavior shown by the Moon. These reports of lunar “anomalies can usually be easily explained using Starry Night to demonstrate the relative locations of Sun, Moon, and horizon. It seems that many people are mystified when the Moon's cusps point upwards instead of horizontally. Starry Night shows clearly why this happens.
Geoff Gaherty
Last month we discussed the concept of Local Hour Angle (LHA) and how we can use Starry Night to indicate the LHA of solar system objects. But the concept of LHA can be used with any celestial object and indeed even with a point in space. The Vernal Equinox is such a point. Among other things, the Vernal Equinox (VE) is the origin of Right Ascension (RA) in the equatorial coordinate system. Thus the VE has RA = 0h 00m. When the VE is on the observer's meridian its LHA is zero.
In Starry Night (Version 6.4) you can illustrate the Vernal Equinox Hour Angle by opening the Options tab and checking the appropriate box as shown above. The graphic above illustrates that the Vernal Equinox passed the meridian 4 hours ago. Any object on the meridian (below the north celestial pole) will thus have an RA of 4 hours. The Local Hour Angle of the Vernal Equinox is also called the sidereal time. In the above example the local sidereal time is 4 hours because Local Sidereal Time equals the Local Hour Angle of the Vernal Equinox. Observers find it useful to know the local sidereal time. If the sidereal time is 6 hours, then any celestial object with an RA of 6 hours will be on the meridian and ideally placed for observation. Further Study What is the relationship between sidereal and solar time? Answer to last month's question: Yes, at the right place and time. You can illustrate this using Starry Night as follows:
Herb Koller
This month, we have three files for your enjoyment: Press the Run Time Forward button to see the Earth revolve around the Sun showing its 23.5 degree rotational axis tilt relative to a perpendicular to its orbital plane, the ecliptic. The axial tilt causes different areas of the Earth to receive different intensities of sunlight at different times of the year. An example showing the planets in the solar system enlarged. Zoom in on Mars. Pedro Braganca
Lying quietly between Gemini and Leo, Cancer is not the most exciting of constellations. However, its modest riches are definitely worth checking out. M44, the Beehive Cluster, is a great target for your binoculars or finderscope. More magnification than that and you'll loose the lovely sense of loose structure. Can you spot it naked eye? Even from your back yard 2,500 lightyears away, you should be able to scoop up M67 in your finderscope or binos. The individual stars of this Mag 6 open cluster will resolve nicely in your telescope's eyepiece. NGC 2775 is a bright spiral galaxy whose core is visible in 8" scopes. Larger scopes will show hints of its spiral-arm structure. Spiral galaxies are the most common kind of galaxy, making up four fifths of all galaxy types, including our own galaxy, the Milky Way. And close by are two more galaxies, NGC 2777, a true gravitational companion of 2775, and NGC 2773 which is four times farther away from us but happens to lie along the same line of sight; you'll need a 10" scope to spot either. At the opposite end of Cancer, Iota Cancri is a nice orange/green double star and well placed to point you just over Cancer's constellation boundary, into Lynx, where the edge-on 10th Mag galaxy NGC 2683 sits. Sean O'Dwyer
|
 |
MAR 2011
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Download this
Fri., March 4
Sat., March 12 
Sat., March 19
Sat., March 26
