Steve’s Virtual Planet

SVC Tip #3 - Planets and trees

This season, the planets are coming around into view again in the evening sky. But, what about trees in the title of this blog? Ahh, if you’re viewing from the suburbs, trees tend to get in the way of objects only a short angular distance from the horizon. The point is that your plans for planet watching need to take your neighborhood tress into account. The tree line will be a factor in determining when your best line of sight will give you access to any of the planets.

Here is a great reason to use one of several interactive planetarium tools to give you a view of the sky you can plan for. My favorite is Sky View Cafe (SVC). (see the other tips here SVC Tip #1 & SVC Tip #2). With Sky View Cafe, you can set your time and date and check in advance how the night’s sky will progress. You can move the time forward and backward to see where the planets will be. And by hovering the mouse pointer over the object, you will see the coordinates in the info band at the bottom. In the case of planets, right ascension and declination aren’t really useful since the planets are drifting across the background of stars. But the altitude and azimuth are very helpful because you can predict where to look for the planets in relation to the horizon and any trees in your viewing site.

Use the azimuth and altitude values of your target and compare with the height of the treeline in that part of the sky. Tweak the time settings to get your target planet in a portion of the sky that is easily viewable. You can even print a sky map from SVC and use that to make an observing plan. Then you can even go one step further and measure the height of the treeline in degrees altitude every 15 degrees of azimuth and make a plot on a circle the same size as the SVC printout. That becomes your reference to use when picking the best time for viewing any object.