Editing Orrery
Warning: You are not logged in.
Your IP address will be recorded in this page's edit history.
Warning: This page is 33 kilobytes long; some browsers may have problems editing pages approaching or longer than 32kb. Please consider breaking the page into smaller sections.
The edit can be undone.
Please check the comparison below to verify that this is what you want to do, and then save the changes below to finish undoing the edit.
Latest revision | Your text | ||
Line 1: | Line 1: | ||
- | + | == Overview == | |
- | The | + | The orrery is a simple open-source application for [[Open development/Maemo roadmap/Fremantle|Maemo 5]] which displays the night (and day!) sky. It is nowhere near as elaborate as, for example, kstars, xephem or stellarium. It is intended to be a small, finger-friendly application, requiring no network connection. The current stable version is 3.2.x (the x just increments when bugs are fixed). The program version is shown on the "Symbol Key" page. |
- | + | ||
- | The star database was extracted from the [[:wikipedia:Hipparcos_catalog|Hipparcos catalog]]. To ease the computational load, the coordinates are not [[:wikipedia:Precession_(astronomy)#Astronomy|precessed]] or [[:wikipedia:Nutation#Of_the_Earth|nutated]] before being displayed. [[:wikipedia:Orbital_elements|Orbital elements]] are used, rather than [[:wikipedia:Ephemerides|ephemerides]], to calculate planet positions. Although this is less accurate, it dramatically reduces the memory footprint. The planet positions are accurate to a few arc minutes, from 3000 BC to 3000 AD. Since the scale on the default display is approximately 8 arc minutes per pixel, these small errors are imperceptible, unless a very large zoom factor is used. | + | The most recent version of the program may be downloaded at |
+ | [https://garage.maemo.org/projects/orrery/ from the garage project page]. The version there may not have gone through the Maemo Community QA testing. The most recent version which has been vetted by the community is available in the Maemo [[Extras]] catalog. This wiki page describes the behavior of the version of the program available in the Extras catalog. | ||
+ | |||
+ | The star database was extracted from the [[:wikipedia:Hipparcos_catalog|Hipparcos catalog]]. To ease the computational load, the coordinates are not [[:wikipedia:Precession_(astronomy)#Astronomy|precessed]] or [[:wikipedia:Nutation#Of_the_Earth|nutated]] before being displayed. [[:wikipedia:Orbital_elements|Orbital elements]] are used, rather than [[:wikipedia:Ephemerides|ephemerides]], to calculate planet positions. Although this is less accurate, it dramatically reduces the memory footprint. The planet positions are accurate to a few arc minutes, from 3000 BC to 3000 AD. Since the scale on the default display is approximately 8 arc minutes per pixel, these small errors are imperceptible, unless a very large zoom factor is used. | ||
== The Display == | == The Display == | ||
- | [[Image:orreryDefaultPage_3.2.png | + | [[Image:orreryDefaultPage_3.2.png|200px|Orrery Default Page]] |
- | The image | + | The image above shows the default display - all stars visible to the unaided eye, with colors for the brightest ones. It's displayed with a [[:wikipedia:Transverse_Mercator|Transverse Mercator projection]] (similar to [[:wikipedia:Norton%27s_Star_Atlas|Norton's Star Atlas]]) which works well with the [[Nokia N900|N900]] in portrait mode. It's a [[:wikipedia:Conformal_transform|conformal transformation]], so the constellations have about the right shapes. The Sun, Moon and planets are plotted, and the Moon is shown with the proper phase. The Sun and Moon are plotted with a size about 3.5 times larger than their true angular size on the sky. That allows the phase of the moon to be shown. |
- | + | The user may chose to have the program display the stars visible at the user's location and at the current time, or at any other position on the earth, or any other time between 3000 BC and 3000 AD. | |
The blue line near the bottom of the display is the horizon. Nothing below that line is visible, but the program plots objects there anyway, because it is often useful to know which objects are just about to rise, and which ones have recently set. | The blue line near the bottom of the display is the horizon. Nothing below that line is visible, but the program plots objects there anyway, because it is often useful to know which objects are just about to rise, and which ones have recently set. | ||
- | |||
=== The orrery as a compass === | === The orrery as a compass === | ||
Line 22: | Line 23: | ||
azimuth is the angle, measured along the horizon, from north through east. So the azimuth of due north is 0, east is 90, south is 180 and west is 270 degrees. By using these azimuth values, the orrery can be used as a celestial compass, if the sky above you is at least partially clear. Notice that the azimuth values are not exactly evenly spaced. This is caused by the distortion introduced by the Transverse Mercator projection. | azimuth is the angle, measured along the horizon, from north through east. So the azimuth of due north is 0, east is 90, south is 180 and west is 270 degrees. By using these azimuth values, the orrery can be used as a celestial compass, if the sky above you is at least partially clear. Notice that the azimuth values are not exactly evenly spaced. This is caused by the distortion introduced by the Transverse Mercator projection. | ||
- | + | If either the sun or moon is visible, you can use the planet compass (under the opts menu) to quickly orient yourself with an accuracy of about 1 degree, | |
You can also use the "Planet Compass" to find directions. If the sun, moon or a planet is visible above the horizon, you can orient the azimuth portion of the planet compass with that object, and use the rest of the compass to find any other direction. | You can also use the "Planet Compass" to find directions. If the sun, moon or a planet is visible above the horizon, you can orient the azimuth portion of the planet compass with that object, and use the rest of the compass to find any other direction. | ||
Line 28: | Line 29: | ||
=== Why does this program put my phone in portrait mode? === | === Why does this program put my phone in portrait mode? === | ||
- | The Transverse Mercator transformation works poorly when the phone is in landscape mode. As we all learned in school, Mercator maps of the earth become very distorted near the earth's poles. For the orrery program, that distortion is unacceptably large when the phone is in landscape mode, because the landscape aspect ratio results in too large a range of azimuth values being displayed. A future version of orrery will support landscape operation, using a different coordinate transformation for that display. | + | The Transverse Mercator transformation works poorly when the phone is in |
+ | landscape mode. As we all learned in school, Mercator maps of the earth become very distorted near the earth's poles. For the orrery program, that distortion is unacceptably large when the phone is in landscape mode, because the landscape aspect ratio results in too large a range of azimuth values being displayed. A future version of orrery will support landscape operation, using a different coordinate transformation for that display. | ||
+ | |||
=== Constellations Display === | === Constellations Display === | ||
- | + | There are two sky display screens defined. By default, one of them shows the display shown above, and the other shows the constellations, and symbolic representations of the solar system objects. Tapping the screen within the upper 4/5 of the display toggles in and out of the constellations page. | |
- | + | [[Image:orreryConstellations_3.2.png|200px|Orrery Constellation Screen]] | |
The constellations are plotted in three colors. The twelve [[:wikipedia:Zodiac|zodiac]] | The constellations are plotted in three colors. The twelve [[:wikipedia:Zodiac|zodiac]] | ||
constellations are plotted in hot pink.The constellations plotted in gold are the classical Greek constellations, as listed in [[:wikipedia:Almagest|Ptolomy's Almagest]] (apart from the zodiac constellations, which are also in the Almagest). The only constellation from the Almagest which is not plotted is Argo Navis, which is not one of the official modern constellations (Argo Navis was broken up into the modern constellations Carina, Puppis and Vela). The remaining constellations, plotted in blue, were added during the last few hundred years. | constellations are plotted in hot pink.The constellations plotted in gold are the classical Greek constellations, as listed in [[:wikipedia:Almagest|Ptolomy's Almagest]] (apart from the zodiac constellations, which are also in the Almagest). The only constellation from the Almagest which is not plotted is Argo Navis, which is not one of the official modern constellations (Argo Navis was broken up into the modern constellations Carina, Puppis and Vela). The remaining constellations, plotted in blue, were added during the last few hundred years. | ||
- | In addition to constellation names and figures, three great circles, the [[:wikipedia:Celestial_Equator|Celestial Equator]] (light yellow), [[:wikipedia:Ecliptic|Ecliptic]] (red) and [[:wikipedia:Galactic_plane|Galactic Plane]] (blue-green), are shown. Solar system objects are shown symbolically (see Mercury, Venus, the Moon and the Sun in the above image). | + | In addition to constellation names and figures, three great circles, the [[:wikipedia:Celestial_Equator|Celestial Equator]] (light yellow), [[:wikipedia:Ecliptic|Ecliptic]] (red) and [[:wikipedia:Galactic_plane|Galactic Plane]] (blue-green), are shown. Solar system objects are shown symbolically (see Mercury, Venus, |
- | + | the Moon and the Sun in the above image). | |
- | === Displaying Asterisms === | + | ==== Displaying Asterisms ==== |
- | [[ | + | There are many [[:wikipedia:Asterism_(astronomy)|informal constellations]] which are widely known, such as the [[:wikipedia:Big_Dipper|Big Dipper]], the [[:wikipedia:Summer_Triangle|Summer Triangle]], etc. The user can choose to display some of these unofficial constellations by selecting "Use Asterisms" from the "Displayed Items" menu. If you know of some nice asterisms that the orrery does not yet display, please send them to orrery.moko@gmail.com, and I'll include them in a future release if I can. The image below shows the Big Dipper and Little Dipper asterisms. |
- | + | [[Image:OrreryAsterisms_3.2.png|200px|Orrery Northern Asterisms]] | |
- | + | ||
- | + | ||
== Panning == | == Panning == | ||
- | + | The image can be panned by tapping your finger in | |
- | The image can be panned by tapping your finger in the bottom 1/5 of the display (excluding menus). The size of the panning step is controlled by how close your finger is to the edge of the display. The program tries to center the azimuth value near where you tap. If you tap near the left or right edges, it pans by the maximum allowed amount, +-40 degrees. Pan steps are | + | the bottom 1/5 of the display (excluding menus). The size of |
+ | the panning step is controlled by how close your finger is | ||
+ | to the edge of the display. The program tries to center | ||
+ | the azimuth value near where you tap. If you tap near the | ||
+ | left or right edges, it | ||
+ | pans by the maximum allowed amount, +-40 degrees. Pan steps are | ||
quantized in increments of 5 degrees. | quantized in increments of 5 degrees. | ||
=== Selecting a New Center Azimuth === | === Selecting a New Center Azimuth === | ||
+ | Panning to a new central azimuth by panning 40 degrees at a time | ||
+ | can be tedious. To make a large change in the display's center | ||
+ | azimuth you may use the azimuth compass. To call up the azimuth | ||
+ | compass, tap near the center of the finger-pan area (bottom 1/5 of | ||
+ | the display) The compass shown below will appear: | ||
- | [[Image:OrreryAzCompass_3.2.png | + | [[Image:OrreryAzCompass_3.2.png|200px|Orrery Azimuth Compass]] |
- | + | The locations of the Sun and Moon are shown if they are above the horizon (if they are too close together, only the Sun is shown). | |
- | + | You may use your finger or stylus to select another center | |
- | The locations of the Sun and Moon are shown if they are above the horizon (if they are too close together, only the Sun is shown). You may use your finger or stylus to select another center azimuth. Keep you finger pressed to the display as you select your new center azimuth - the selected azimuth will be shown by a white pointer on the inside of the compass circle. Once you release pressure on the screen, the compass will disappear, and the display will be redrawn. | + | azimuth. Keep you finger pressed to the display as you select |
+ | your new center azimuth - the selected azimuth will be shown by | ||
+ | a white pointer on the inside of the compass circle. Once you release pressure on the screen, | ||
+ | the compass will disappear, and the display will be redrawn. | ||
The azimuth compass cannot be accessed if the display is zoomed. | The azimuth compass cannot be accessed if the display is zoomed. | ||
- | |||
== Main Menu == | == Main Menu == | ||
- | [[Image:orreryMainMenu-3.3.png | + | [[Image:orreryMainMenu-3.3.png|200px|Orrery Main Menu]] |
The main dropdown menu for the orrery has six options: | The main dropdown menu for the orrery has six options: | ||
- | |||
=== Other Pages === | === Other Pages === | ||
- | |||
- | |||
The "Other Pages" option takes you to a menu that allows you to display things other than the night sky. With the exception of the flashlight pages, which are dismissed by tapping anywhere on the screen, the "Other Pages" are dismissed by curved arrow in the upper right hand corner. | The "Other Pages" option takes you to a menu that allows you to display things other than the night sky. With the exception of the flashlight pages, which are dismissed by tapping anywhere on the screen, the "Other Pages" are dismissed by curved arrow in the upper right hand corner. | ||
- | + | ||
+ | [[Image:orreryOtherPagesMenu-3.1.png|200px|Orrery Other Pages Menu]] | ||
==== Flashlight Modes ==== | ==== Flashlight Modes ==== | ||
- | The "White Flashlight" button paints the entire screen white, and the "Red Flashlight" button paints the entire screen red. Both may be used as a flashlight, but the red one is best if you are trying to preserve your [[:wikipedia:Night_vision|night vision]]. | + | The "White Flashlight" button paints the entire screen white, and the |
+ | "Red Flashlight" button paints the entire screen red. Both may | ||
+ | be used as a flashlight, but the red one is best if you are trying | ||
+ | to preserve your [[:wikipedia:Night_vision|night vision]]. | ||
- | ==== | + | ==== Sunrise and Moon ==== |
- | + | The "Sun and Moon" button displays a page giving the sun and moon positions, rise and set times, phase, etc. for five days, centered on today: | |
- | + | [[Image:orrerySunAndMoon_3.2.png|200px|Sun and Moon Information page]] | |
- | The highlighted date is the current UT date (unless the time menu has been used to select a different time). The highlighted rise and set times are the next ones which will occur at your location. Of course, that may be on a different UT date (for example, during daylight hours, the next sunrise will be tomorrow). The times are shown as UT, which may annoy people. UT is used because the orrery allows you to select any location on the earth, and any time from 3000 BC until 3000 AD. It would be very difficult to keep track of all the timezone, daylight savings change dates, etc. for that time range! So I have wimped out, and displayed UT, which is always reasonably well defined. | + | The highlighted date is the current [[:wikipedia:Universal_time|Universal Time]] (UT) date (unless the time menu has been used to select a different time). The highlighted rise and set times are the next ones which will occur at your location. Of course, that may be on a different UT date (for example, during daylight hours, the next sunrise will be tomorrow). The times are shown as UT, which may annoy people. UT is used because the orrery allows you to select any location on the earth, and any time from 3000 BC until 3000 AD. It would be very difficult to keep track of all the timezone, daylight savings change dates, etc. for that time range! So I have wimped out, and displayed UT, which is always reasonably well defined. |
The current sun and moon positions shown are geocentric - no topocentric correction has been applied. However topocentric corrections are applied when rise and set times are calculated, so they should be reasonably accurate for a specific location on earth. | The current sun and moon positions shown are geocentric - no topocentric correction has been applied. However topocentric corrections are applied when rise and set times are calculated, so they should be reasonably accurate for a specific location on earth. | ||
Line 97: | Line 111: | ||
This page also shows the UT date and time of the four major moon phases ([[:wikipedia:Lunar_phases#Names_of_lunar_phases|New, First Quarter, Full and Last Quarter]]) for a time span of 10 [[:wikipedia:Lunar_month|lunar months]], centered on the current time (which of course can be changed with the time menu). The nearest time and date when each phase will occur is highlighted. | This page also shows the UT date and time of the four major moon phases ([[:wikipedia:Lunar_phases#Names_of_lunar_phases|New, First Quarter, Full and Last Quarter]]) for a time span of 10 [[:wikipedia:Lunar_month|lunar months]], centered on the current time (which of course can be changed with the time menu). The nearest time and date when each phase will occur is highlighted. | ||
- | |||
- | |||
- | |||
- | |||
==== Symbol Key ==== | ==== Symbol Key ==== | ||
Line 108: | Line 118: | ||
==== Big Moon Calendar ==== | ==== Big Moon Calendar ==== | ||
- | + | The Big Moon Calendar is a graphic display of the phase of the moon for | |
+ | each day from 10 months before the current month, until 10 months after | ||
+ | the current month (roughly 640 days), as shown below: | ||
- | + | [[Image:orreryBigMoonCalendar_3.2.png|200px|Big Moon Calendar]] | |
- | Each column shows one month, and the day number is shown for each row. At the top and bottom of each column is shown the first letter of the name of the month shown in the column. Two vertical green lines separate years. The current Universal Time date is outlined in a red box. | + | Each column shows one month, and the day number is shown for each row. |
- | + | At the top and bottom of each column is shown the first letter of the | |
+ | name of the month | ||
+ | shown in the column. Two vertical green lines separate years. | ||
+ | The current Universal Time date is outlined in a red box. | ||
==== This Month's Moons ==== | ==== This Month's Moons ==== | ||
- | + | The This Moon's Moons page shows the phase of the moon for each day of a particular month. By default, the current month is shown, but one may use the arrow buttons to pan through the months. | |
- | + | [[Image:orreryMonthlyMoonCalendar_3.2.png|200px|Monthly Moon Calendar]] | |
- | Both moon calendars show "[[:wikipedia:Blue_Moon|Blue Moons]]", which are (according to the most commonly used definition) the second full moon in a calendar month which has two full moons. Both images | + | Both moon calendars show "[[:wikipedia:Blue_Moon|Blue Moons]]", which are (according to the most commonly used definition) the second full moon in a calendar month which has two full moons. Both images above show the Blue Moon which falls on New Year's Eve, 2009. |
- | + | ||
==== Meteor Showers ==== | ==== Meteor Showers ==== | ||
- | |||
- | |||
This display shows information for all the [[:wikipedia:Meteor_shower|meteors showers]] which will occur during the current year. Remember that to see a meteor shower, you must travel to a site that has a very dark sky. In a city, few meteors will be seen even during a shower. | This display shows information for all the [[:wikipedia:Meteor_shower|meteors showers]] which will occur during the current year. Remember that to see a meteor shower, you must travel to a site that has a very dark sky. In a city, few meteors will be seen even during a shower. | ||
- | The items shown on the Meteor Showers page are | + | [[Image:orreryMeteorShower-3.1.png|200px|Meteor Showers]] |
+ | |||
+ | The items shown on the Meteor Showers page are | ||
# the name of the meteor shower | # the name of the meteor shower | ||
# the abbreviation used for this shower when its [[:wikipedia:Meteor_shower#The_radiant_point|radiant]] is plotted on the sky display | # the abbreviation used for this shower when its [[:wikipedia:Meteor_shower#The_radiant_point|radiant]] is plotted on the sky display | ||
Line 141: | Line 155: | ||
the horizon to not appreciably brighten the sky. | the horizon to not appreciably brighten the sky. | ||
- | The Meteor Showers page shows information for all showers, the large majority of which are really minor events. Even when a meteor shower is not occurring, you can expect to see 4 to 10 meteors per hour. Many of the showers listed do not even double that background rate, and are of interest only to serious meteor enthusiasts. If you just want to go out and see some meteors for fun, it's best to select a shower with a rate of at least 50 meteors per hour, and to watch it on or very near the date of the shower's maximum. | + | The Meteor Showers page shows information for all showers, the large majority of which are really minor events. Even when a meteor shower is not occurring, you can expect to see 4 to 10 meteors per hour. Many of the showers listed do not even double that |
+ | background rate, and are of interest only to serious meteor enthusiasts. If you just want to go out and see some meteors for fun, it's best to select a shower with a rate of at least 50 meteors per hour, and to watch it on or very near the date of the shower's maximum. | ||
Each line of the display describes a separate shower. If the shower currently in progress, the line is shown in green - bright green if there will be 2 or more hours of dark sky tonight, and dark green otherwise. If the shower is not currently underway, it will be shown in a cream color if on the night of the shower's maximum, the sky will be dark for at least 2 hours. Otherwise the shower information will be shown in grey, indicating that this year is not a good one to observe that particular shower. | Each line of the display describes a separate shower. If the shower currently in progress, the line is shown in green - bright green if there will be 2 or more hours of dark sky tonight, and dark green otherwise. If the shower is not currently underway, it will be shown in a cream color if on the night of the shower's maximum, the sky will be dark for at least 2 hours. Otherwise the shower information will be shown in grey, indicating that this year is not a good one to observe that particular shower. | ||
Line 153: | Line 168: | ||
==== Planet Compass ==== | ==== Planet Compass ==== | ||
- | |||
- | |||
The Planet Compass page graphically shows where each of the planets is at the current time. | The Planet Compass page graphically shows where each of the planets is at the current time. | ||
+ | |||
+ | [[Image:OrreryPlanetCompass-3.1.png|200px|Moon Calendar]] | ||
The image has one complete circle, which shows the planet azimuth, and one semicircle, which shows the [[:wikipedia:Altitude_(astronomy)|elevation]]. | The image has one complete circle, which shows the planet azimuth, and one semicircle, which shows the [[:wikipedia:Altitude_(astronomy)|elevation]]. | ||
- | The azimuth circle has blue triangles marking the four [[:wikipedia:Cardinal_points|cardinal points]]: North, South, East and West. There are small tick lines at the NE, SE, SW and NW directions, as well as a small dot every 10 degrees. The planet symbols are shown with lines projecting to their current azimuth. The line is white if the planet is above the horizon, and red if it is below the horizon. | + | The azimuth circle has blue triangles marking the four [[:wikipedia:Cardinal_points|cardinal points]]: North, South, East and West. There are small tick lines at the NE, SE, SW and NW directions, as well as a small dot every 10 degrees. The planet symbols are shown with lines projecting to their current azimuth. The line is white if the planet is above the horizon, and red if it is below the horizon. |
The elevation semicircle has blue triangles marking the directions of the Zenith, Horizon and Nadir. Small dots are shown every 10 degrees, and there are short lines at +-45 degrees. As with the azimuth circle, lines connect the planet symbols to their current elevations. | The elevation semicircle has blue triangles marking the directions of the Zenith, Horizon and Nadir. Small dots are shown every 10 degrees, and there are short lines at +-45 degrees. As with the azimuth circle, lines connect the planet symbols to their current elevations. | ||
- | Below the compass graphic, the name, [[:wikipedia:Hour_angle|Hour Angle]] (HA) rising time and azimuth, transit time and elevation, and setting time and azimuth is shown for each planet. The name of the planet is | + | Below the compass graphic, the name, [[:wikipedia:Hour_angle|Hour Angle]] (HA) rising time and azimuth, transit time and elevation, and setting time and azimuth is shown for each planet. The name and HA of the planet is highlighted if the planet is above the horizon. The time of the next event - rising, transiting or setting, is also highlighted |
- | + | for each planet. | |
==== Solar System ==== | ==== Solar System ==== | ||
Line 172: | Line 187: | ||
===== Schematic Solar System View ===== | ===== Schematic Solar System View ===== | ||
- | |||
- | |||
This button presents a schematic view of the Solar System, showing the locations of the earth, the earth's moon and the other planets in their orbits around the sun. The view is schematic in the sense that the orbit radii and planet sizes are not shown to scale. However the positions of the objects within their orbits are correct (the heliocentric [[:wikipedia:Ecliptic_longitude|ecliptic longitudes]] are correct). | This button presents a schematic view of the Solar System, showing the locations of the earth, the earth's moon and the other planets in their orbits around the sun. The view is schematic in the sense that the orbit radii and planet sizes are not shown to scale. However the positions of the objects within their orbits are correct (the heliocentric [[:wikipedia:Ecliptic_longitude|ecliptic longitudes]] are correct). | ||
+ | |||
+ | [[Image:OrrerySchematicSolSys-3.1.png|200px|Solar System View (schematic)]] | ||
Several buttons are drawn at the bottom of the display, which allow you to show an animation of the motion of the Solar System objects for several time increments. Showing the motion of planets in this way is what mechanical orreries do. | Several buttons are drawn at the bottom of the display, which allow you to show an animation of the motion of the Solar System objects for several time increments. Showing the motion of planets in this way is what mechanical orreries do. | ||
- | |||
===== To-Scale Solar System View ===== | ===== To-Scale Solar System View ===== | ||
- | |||
- | |||
This button displays the Solar System with the planet orbits shown with | This button displays the Solar System with the planet orbits shown with | ||
- | the proper relative sizes. The orbits are also plotted as [[:wikipedia:Ellipse|ellipses]] in this display, with the correct eccentricity and orientation. The moon is not plotted, because it would be too close to the earth to display if any of the planet orbits were completely shown. Because Neptune's orbit is nearly 100 times larger than Mercury's, it is not possible to display all of the planet orbits simultaneously. There are "Zoom In" and "Zoom Out" buttons which allow you to select which proper subset of planet orbits is shown. The current position of each planet in its orbit is shown. Also plotted are grey lines connecting the Sun to each orbit, terminating with a white dot at the position of the planet's [[:wikipedia:Perihelion#Planetary_perihelion_and_aphelion|perihelion]] (where it is closest to the sun in its orbit). The image | + | the proper relative sizes. The orbits are also plotted as [[:wikipedia:Ellipse|ellipses]] in this display, with the correct eccentricity and orientation. The moon is not plotted, because it would be too close to the earth to display if any of the planet orbits were completely shown. Because Neptune's orbit is nearly 100 times larger than Mercury's, it is not possible to display all of the planet orbits simultaneously. There are "Zoom In" |
- | + | and "Zoom Out" buttons which allow you to select which proper subset of planet orbits is shown. The current position of each planet in its orbit is shown. Also plotted are grey lines connecting the Sun to each orbit, terminating with a white dot at the position of the planet's [[:wikipedia:Perihelion#Planetary_perihelion_and_aphelion|perihelion]] (where it is closest to the sun in its orbit). The image below shows the display when the outermost plotted planet is Mars. Note that the orbits of Mercury and Mars are quite non-circular: | |
- | + | [[Image:OrreryToScaleSolSys-3.1.png|200px|Solar System View (to-scale)]] | |
- | + | ||
- | [[Image: | + | |
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
=== Displayed Items === | === Displayed Items === | ||
- | The "Displayed Items" page allows you to configure the display, selecting such things as the faintest magnitude object displayed, whether constellation lines are plotted, whether or not star names are displayed, etc. | + | The "Displayed Items" page allows you to configure the display, selecting |
+ | such things as the faintest magnitude object displayed, whether constellation | ||
+ | lines are plotted, whether or not star names are displayed, etc. | ||
==== Deep Sky Objects ==== | ==== Deep Sky Objects ==== | ||
- | |||
- | |||
If you select "Deep Sky Obs" from the "Displayed Items" menu, you will be shown some of the brightest [[:wikipedia:Deep_sky_object|Deep Sky Objects]]. Deep Sky Objects are objects such as galaxies, expelled envelopes of dying stars, clusters of young stars and luminous gas. A few, such as the Andromeda Galaxy, are visible to the unaided eye. Many more are visible with binoculars or a small telescope. The orrery shows all [[:wikipedia:Messier_object|Messier objects]], and many other well known bright nebulae and star clusters. The image bellow shows the Messier objects in Sagittarius. | If you select "Deep Sky Obs" from the "Displayed Items" menu, you will be shown some of the brightest [[:wikipedia:Deep_sky_object|Deep Sky Objects]]. Deep Sky Objects are objects such as galaxies, expelled envelopes of dying stars, clusters of young stars and luminous gas. A few, such as the Andromeda Galaxy, are visible to the unaided eye. Many more are visible with binoculars or a small telescope. The orrery shows all [[:wikipedia:Messier_object|Messier objects]], and many other well known bright nebulae and star clusters. The image bellow shows the Messier objects in Sagittarius. | ||
+ | |||
+ | [[Image:orrerySagitarriusClusters.png|200px|Star clusters in Sagittarius]] | ||
===== Adding Your Own Deep Sky Object List ===== | ===== Adding Your Own Deep Sky Object List ===== | ||
- | You may add your own list of deep sky objects to be plotted. Simply create a file within the directory | + | You may add your own list of deep sky objects to be plotted. Simply create a file within the directory /usr/share/orrery/deepSky/ with any name. The file should contain lines of text with the format: |
name HH MM SS.SS DD MM SS.S type mag | name HH MM SS.SS DD MM SS.S type mag | ||
- | where name is the object name, which may not include white space, HH MM SS.SS is the Right Ascension, DD MM SS.S is the declination (do not include a + sign for positive declinations) "type" is an integer specifying the type of object | + | where name is the object name, which may not include white space, HH MM SS.SS is the Right Ascension, DD MM SS.S is the declination (do not include a + sign for positive declinations) "type" is an integer specifying the type of object. 0 = [[:wikipedia:Supernova_remnant|Supernova Remnant]], 1 = [[:wikipedia:Globular_cluster|Globular Cluster]], 2 = [[:wikipedia:Open_cluster|Open Cluster]], 3 = [[:wikipedia:Nebula#Diffuse_nebulae|Diffuse Nebula]] ([[:wikipedia:H_II_region|HII region]], etc.), 4 = [[:wikipedia:Planetary_nebula|Planetary Nebula]], and 5 = [[:wikipedia:Galaxy|Galaxy]]. The "mag" is the visual magnitude. The orrery program currently does nothing with the visual magnitude, but future versions may use it. |
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | The "mag" is the visual magnitude. The orrery program currently does nothing with the visual magnitude, but future versions may use it. | + | |
==== Meteor Radiants ==== | ==== Meteor Radiants ==== | ||
- | If you select Meteor Radiants, then the radiant position for any meteor showers which are now occurring will be plotted. The radiant is the position in the sky from which meteors seem to emerge during a shower - it's the best place in the sky to look for meteors.The radiant is plotted in white if more than 50 meteors per hour are expected under optimal viewing conditions, cream-color if 20 or more meteors per hour are expected, and grey if fewer then 20 meteors per hour are expected. Note that these are meteor rates for the date of the shower maximum - see the Meteor Showers page for more information. The radiant position usually changes as the shower progresses. The orrery takes that into account when plotting the radiant. | + | If you select Meteor Radiants, then the radiant position for any meteor showers which are now occurring will be plotted. The radiant is the position in the sky from which meteors seem to emerge during a shower - it's the best place in the sky to look for meteors.The radiant is plotted in white if more than 50 meteors per hour are expected under optimal |
+ | viewing conditions, cream-color if 20 or more meteors per hour are expected, and grey if fewer then 20 meteors per hour are expected. Note that these are meteor rates for the date of the shower maximum - see the Meteor Showers page for more information. The radiant position usually changes as the shower progresses. The orrery takes that into account when plotting the radiant. | ||
==== Changing the Magnitude Limit ==== | ==== Changing the Magnitude Limit ==== | ||
- | The magnitude scale for expressing the brightness of stars and planets is explained [[:wikipedia:Apparent_magnitude|in | + | The magnitude scale for expressing the brightness of stars and planets is explained [[:wikipedia:Apparent_magnitude|in a Wikipedia article]]. It is one of the oldest |
measurement systems still in use today. | measurement systems still in use today. | ||
By default, the orrery displays every star a person with excellent eyesight located in a very dark area on a moonless night can see. If your observing conditions are less ideal than that, it can be helpful to use the "Mag. Limit" field in the item menu to lower | By default, the orrery displays every star a person with excellent eyesight located in a very dark area on a moonless night can see. If your observing conditions are less ideal than that, it can be helpful to use the "Mag. Limit" field in the item menu to lower | ||
- | the limit of the faintest object plotted. | + | the limit of the faintest object plotted. |
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
- | + | ||
=== Change Time === | === Change Time === | ||
Line 403: | Line 273: | ||
This button brings up a page with a few basic instructions for operating the program. It does not require a network connection. | This button brings up a page with a few basic instructions for operating the program. It does not require a network connection. | ||
- | |||
- | |||
- | |||
- | |||
- | |||
- | |||
- | |||
- | |||
- | |||
== Touchscreen Gestures == | == Touchscreen Gestures == | ||
Line 448: | Line 309: | ||
=== Symbol Key === | === Symbol Key === | ||
- | + | If you select "About Orrery / Symbol Key" from the "opts" menu, you will be shown an annotated list of the symbols used by the orrery, which is reproduced below: | |
- | + | [[Image:orrerySymbolKey-3.1.png|200px|Symbols used by the orrery]] | |
- | NOTE: the current version is 3. | + | NOTE: the current version is 3.1. |
=== Planet Symbols === | === Planet Symbols === | ||
Line 461: | Line 322: | ||
=== Plotted Lines === | === Plotted Lines === | ||
- | The dotted yellow line is the Celestial Equator, the intersection of the Earth's equatorial plane with the celestial sphere. The red dotted line is the Ecliptic. The Ecliptic is the intersection of the Earth's orbital plane with the celestial sphere. The Ecliptic is also the path of the Sun across the sky, and the intersection points between the Celestial Equator and the Ecliptic are where the Sun is at the time of an equinox. | + | The dotted yellow line is the Celestial Equator, the intersection of the Earth's equatorial plane with the celestial sphere. The red dotted line is the Ecliptic. The Ecliptic is the intersection of the Earth's orbital plane with the celestial sphere. The |
- | + | Ecliptic is also the path of the Sun across the sky, and the intersection points between the Celestial Equator and the Ecliptic are where the Sun is at the time of an equinox. Constellations lying along the Ecliptic plane are zodiac constellations. The planets and the Moon are always near, but usually not exactly on, the Ecliptic. The blue-green dotted line is the Galactic Plane, the intersection of the plane of the Milky Way's disk and the celestial sphere. | |
== Displaying Stars Too Faint for the Unaided Eye to See == | == Displaying Stars Too Faint for the Unaided Eye to See == | ||
Line 481: | Line 342: | ||
The plot below shows [[:wikipedia:Hyades_(star_cluster)|Hyades star cluster]] with limiting magnitudes of 6.6 (left) and 9.0 (right). | The plot below shows [[:wikipedia:Hyades_(star_cluster)|Hyades star cluster]] with limiting magnitudes of 6.6 (left) and 9.0 (right). | ||
- | [[Image:orreryHyadesMagComp.png | + | [[Image:orreryHyadesMagComp.png|400px|Orrery Catalogs]] |
Remember, there's no reason at all to install the hipparcos_9.0.dat file unless you plan to do star gazing with binoculars or a small telescope. | Remember, there's no reason at all to install the hipparcos_9.0.dat file unless you plan to do star gazing with binoculars or a small telescope. | ||
- | |||
== Chinese Color Scheme == | == Chinese Color Scheme == | ||
- | In traditional Chinese astronomy, the zodiac is known as the Yellow Way, and the celestial equator is known as the Red Way. If you want the orrery to use that color scheme for great circles and constellations, edit the file <code>/usr/share/orrery/config</code>, and make the first | + | In traditional Chinese astronomy, the zodiac is known as the Yellow Way, and the celestial equator is known as the Red Way. If you want the orrery to use that color scheme for great circles and constellations, edit the file <code>/usr/share/orrery/config</code>, and make the first lineread |
CHINESE_COLOR_SCHEME 1 | CHINESE_COLOR_SCHEME 1 |
Learn more about Contributing to the wiki.