7 useful astronomy resources

Finding out what's happening up in the sky often involves using a variety of resources, such as books, star charts, astronomy software, apps, etc. Some may present you with a bunch of number or unfamiliar terminology. Here's some of my favourite online resources, which are relatively easy to use and interpret as well as some new ones which I just recently discovered.

1. Sky and Telescope: Interactive Sky Chart (JAVA applet)

This popular astronomy magazine has many useful features on its website. The Sky Chart provides a relatively simple view of which stars and planets you can expect to see at any time of day or year.

After registering your details on the site and opening the sky chart, you first have to set your location/hometown and timezone (i.e. Singapore, GMT+8). Once that's done, you can alter the time and date on the side panel and watch which objects appear during that particular time.

2. Skymaps.com

This website provides a static but more detailed starmap for each month, in an easily printable pdf format. The important part is to pick the right map for your part of the world, i.e in Singapore, you'll need the Equatorial Edition.

3. Moon Phase Images

Enter your desired date and time, and receive a simple image of the moon phase on that particular date.

4. NASA Solar System Simulator

View any object in the solar system as they would appear from any other object. For example, look at the rings of Saturn as seen from its largest moon Titan or how the Sun and other planets look like from Pluto.

I often use it to get an overall view of the whole solar system, to see the arrangement of planets during significant alignments or the position of current space probes, like New Horizon, which is on its way to Pluto.

On the menu page, you need to select the object you wish to view and  where you want to view it from, as well as the size of the field of view.

NASA Solar System  Simulator -  field of view 45 degrees - wide enough to see Pluto, but too far to see inner planets

NASA Solar System - field of view 5 degrees - only wide enough to see up to Jupiter. but can show position of inner planets.

5. Dynamic Diagrams Solar System (SWF/FLASH)

I recently remembered this rather nice-looking solar system model. Although the size and distances of the planets is not to scale, their positions are accurate.

Just drag the arrow indicating the date around the outer edge or select the running speed on the control bar in the top left corner and watch the planets dance around each other.

The two options at the bottom right corner (Copernican and Tychonian) give two slightly different views: Copernican shows the more realistic view with the Sun at the centre, whereas Tychonian puts Earth at the centre, allowing you to see the position of planets as seen from Earth.

6. The Planets Today

Very similar to dynamic diagrams, except with more options that allow you to adjust the size and scale of the planets. 

Both Planets Today and Dynamic Diagrams appear to be used for astrology, as they provide information regarding the position of the planet's with respect to zodiac star signs (Leo, Gemini, etc). Whilst the zodiac does represents actual constellations, the position of the astrological star signs given in these two sites is scientifically inaccurate and out of date. However, you have to option to remove the zodiac star signs from each diagram.

Finally, for a bit of solar system exploring fun try Ace of Space and pilot your space ship around the solar in the fastest possible time.

Observing Satellites

Orbiting around our planet are thousands of electronic satellites that make great targets for urban astronomers like ourselves. And, there are a number of useful tools and apps that will help you locate them.

A common misconception is that the easiest satellites to spot are those in geosynchronous orbit (GSO) which  stay positioned above the same place on Earth. This is not true, as these satellites orbit at a distance of 35,786km, from which they cannot be seen as they have no light of their own.
The easiest satellittes to spot are those closest to us in low earth orbit (LEO), orbitting between 200km-2000km above the Earth. Such low orbits cause them to travel around the Earth 10 or 15 times every day, occassional travelling above Singapore.

A good website to find dates and timings of visible satellittes is Heavens-Above.
Once there, the first thing you must do is set your location. This is done under the "Configuration" menu: click "from database" and type in and select your city .i.e. Singapore.

You can be more precise by manually inputting your longitude and latitude or selecting from the map, however I often found these options give you the timings in UT (universal time/GMT) which is minus 8 hours from Singapore time,which is a be a bit confusing. Selecting your city from the database gives the local timings.

Once your location is set, just click on a satellite name. The brightest satellites are usually the International Space Station (ISS), Hubble Space Telescope (HST), Iridium Satellites (very bright communication satellites) or maybe China's Tiangong 1 space station.

After making a selection you will be presented with a table of information for all the visible passes for that particular time period.
This information includes the brightness or magnitude. The lower the number the brighter the object will be. Negative numbers indicates that the satellite will be brighter than most stars.
Satellites with magnitudes greater than 2 or 3 maybe difficult to spot in a light polluted environment.

The timings are given in 24hour format (HH:MM:SS) along with the altitude (height) and azimuth (direction) of the satellite at that particular time. Some satellites are visible for several minutes, so their start and end timings/positions are stated separately.
The highest possible altitude is 90 degree (directly overhead). Altitudes below 30 degrees may not be visible from some locations due to trees or tall buildings.

Iridium Satellites (http://en.wikipedia.org/wiki/Iridium_satellite_constellation) are only visible for a few seconds so usually only one time period is stated. Because of the shape of their solar panels, they only reflect the sunlight for short period of time but the reflection is very intense and quickly fades from view, this is known as an Iridium Flare. 

Iridium satellite 

Apps for Satellite Tracking

One of the most useful ways to find satellites is using a smartphone app. I've only tried one so far called SatTrack for Android phones from Goggle Play Store:
Again, the first thing is to set your location using your GPS, once that's done you'll get a list of all visible satellites passing over your location. This even includes various rockets and other space junk left behind in orbit. Its best to use the settings to filter the most visible ones. Basically, anything brighter (lower) than magnitude 2.5 and higher than 30 degrees in altitude should be easy to find.

Once you select a satellite, you'll be presented with the magnitude, timings, altitude and azimuth as well as a handy compass which indicates the location and direction in which the satellite will travel across the sky (the purple line).

The app sometimes sends you notifications, when a satellite pass is due to start but you can also select an extra alarm/vibrate setting for those satellites you do not want to miss.

SatTrack app is free and there's also a paid version (without ads) but there many other satellite apps on the android market. There are also some on iTunes for iPhone users, this include: GoSatWatch and Satellites although they're not free,

Look out for those bright Iridium Flares and ISS sightings over the coming week.

New Toys

Recently, I've been on the lookout for new models and props related to astronomy that can be used in some of our school programmes, like are planetarium shows and large group demonstrations. During a search on the internet I came across a large scale inflatable solar system.
At first it looked like it was only available on overseas websites like Amazon but later I found a local supplier here in Singapore, The Learning Store/Expenovate.

The next day I went down there to take look, and bought the last two sets of their current stock. I intend to use one set for  some interactive play during the introduction to our planetarium programme for preschoolers. Currently I'm using a series of Styrofoam balls and marbles to illustrate the location and size of the planets in the solar system, the inflatable planets however are much more visually appealing and you can bounce them around.



The second set will be ideal for my upcoming talk on "the planets" for the NLB, which I'll be conducting as apart of their astronomy month at Jurong East Library on Saturday 2nd June.

Back at Science Centre,  the solar systems attracted quite alot of attention from my fellow scobbers and colleagues who were in the office at the time. Kin Guan and myself set about inflating the planets inside our cubicle area using the supplied footpump, which made a loud high pitch sound every time we stepped on it. One of our colleagues found this particularly disturbing, as it is similar to the sound of scratching a blackboard with your fingernails (does anyone still use blackboards?), something known to send shivers down your spine, although I think my colleague used the phrase "makes me resonate" :/

We inflated the rest of the planets in the walkway outside and once finished brought them back into the office where several others contributed other ways of using them, like attempting to spin each planet on one finger.

The inflatable solar system is a nice set for visual demonstrations and explaining the solar system layout, however the sizes are not to scale, although the gas planets (Jupiter, Saturn, Uranus, Neptune) are quite close.
Of course the Sun is so big its hard to represent its true size.  Sometimes I will still use marbles and Styrofoam balls to represent the size of the rocky planets like Earth, Mars, Venus and Mercury, which are incredibly small compared to the gas giants.

I guess its hard to find a really accurate solar system model because of the large variation in size, not to mention the huge distances between the planets.

As often happens when shopping, you sometimes come back with more than you intended to buy. Likewise, whilst at the learning store I also picked up these colourful posters which I thought would be nice to display inside the observatory:

Google Sky Map for Android Phones

There are plenty of Sky Map apps on the iPhone, but how about the droids? I recently came across a really cool one by Google.

Google Sky Map allows you to explore the night sky just by pointing your phone to space. The screen serves as a window onto the sky, whereby you can explore the relative positions of planets, stars, constellations, and more, in realtime.




In the auto mode, Google Sky Map works just like a compass. As you move the phone, the view on the screen moves. Pointing the phone to a particular star allows one to find out its name. To find out what our fellow stargazers can see from the other side of the earth right now, point the phone to the ground. To find out what is in the sky in the afternoon, point the phone to the ceiling if you are indoors.

If you prefer, the traditional manual mode is also available. Just open up a zoomed in sky map (the whole celestial sphere) and explore by sliding your fingers across the screen.

An extensive database is also available for you to search for a particular object in the sky.

Everytime I play with this app, I am mesmerized by the dazzling array of stars that surrounds the Earth from every angle, and at any time of the day.

If you are holding on to an Android phone, go try it out now!