Polar alignment is a necessary step in observing with a telescope. The earth rotates, and this can cause the stars to appear to shift position, which makes finding them difficult or impossible.
Polar alignment ensures that the telescope will show stars as they are in the sky rather than how they would be seen from earth. You’ve just taken your first step in becoming an astronomy enthusiast.
Today, we provide you with the essential information about how to polar align a telescope during the day to start enjoying your new hobby.
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How To Polar Align a Telescope During the Day
When attempting to polar align your telescope during the daytime, below are the recommended steps you can follow.
Step #1: Find a Location Where You Can See the Celestial Pole and Horizon
You can see the celestial pole by going to a location where you have both an unobstructed view of the sky and a reasonably flat horizon. Put your telescope on a tripod and set it up.
Use your hand as a measure, with one finger for every 10 degrees off vertical that you are looking from the earth’s centerline. Point your polar finder scope at Polaris or Sigma Octantis if they are visible in the sky, then adjust the declination setting so that the pointer over the pole points to 0°. Turn off any tracking device.
Step #2: Determine the Azimuth of Polaris (North Star)
Relative to the horizon in your area, you can find it by counting how many fingers you put up and then estimate how high in the sky Polaris is at that time of day. Find a star in the sky near the celestial pole and use this to align your telescope during daylight hours.
Once you have found that star, point your scope, so it is pointing at that exact spot in the sky or close as possible. If it is not visible, align your finderscope on a star close to Polaris’ position or use an app like Stellarium (iPad/iPhone).
Now sight and scope where the mount should be pointed on earth using landmarks such as buildings, trees, or mountains. Check that you are using true south and east by looking for other stars near the same altitude as they will point in these directions.
- For every finger, there are about 15 degrees off vertical. In this example, we say seven fingers.
- Point the polar finder scope at Polaris
- Adjust the declination setting so that the pointer over the pole indicates 0°. You can adjust this by turning a thumbscrew until it reads zero degrees or close to it on your polar finder’s reticle crosshairs.
Step #3: Use Your Compass To Measure How Far Away Polaris Is From the Horizon (in Degrees)
Your mount should be pointing at the horizon, and your telescope’s polar axis will need to match that same angle. Once you are satisfied that the mount is pointing in the right direction, use a bubble level or other means to ensure your mount is flat and parallel with the earth’s horizon.
- Set the right ascension setting to match your latitude.
- Now turn on the low-power eyepiece and find Polaris using its faint magnitude.
- You can also try estimating how far off from true north Polaris is by looking at how much the star is tilted from vertical.
- It should be exactly at a right angle or close to it, within a few degrees.
- If you are off by more than about five degrees, use your altitude setting on the RA dial and make minor adjustments until Polaris is aligned correctly.
- The telescope will now find objects for you when you are polar aligned.
Step #4: Find Your Latitude and Longitude Using Google Maps or an Online Tool
Your latitude is the most important of these two. Point your telescope back to where it initially was pointed at before you aligned it during daylight hours.
Google maps and similar online tools are excellent for finding your latitude. They provide a clear understanding of where you live.
One way to figure out your longitude, which you can use in conjunction with a map for more accuracy, is by using an online tool. Type in how far north or south you are from the equator and hit calculate, then put that number into Google Maps.
Step #5: Measure How Many Degrees Below the Horizon Polaris Is at in Your Location (in Degrees)
Here’s a quick way to measure how many degrees below the horizon Polaris is at in your location:
- Stand where you are looking up and out into space, away from buildings that might obstruct it or get as close as possible.
- Find some landmark or object like an edge of a building. Once found, use this point to line yourself up with one side of it by lining both feet along its margin without stepping off the ground.
- Once aligned, turn around, so you’re facing back towards earth.
- Using something convenient for measurement, such as your arm span, find any signposts nearby.
- Hold out arms parallel to each other and then make sure they don’t touch.
- Use hands together with palms down resting palm-side.
Step #6: Subtract the Number Obtained Above From 90
This will give you the number of minutes that need to be added to your telescope’s polar alignment process during daylight hours when it would otherwise be dark outside. Verify that you are aligned by observing certain stars, planets, or other celestial bodies in the sky and comparing them to what is shown on your star map or polar alignment scope.
Conclusion
Once you have completed the alignment process, your telescope will be tracking with earth’s rotation. Polaris should stay in a fixed position relative to the earth and not move as it rotates around on its axis, and you’ll be able to take long exposure photos without star trails!
Now that you know how to polar align your telescope during the day, why not head outside and see what you can find in our solar system. If you’re feeling adventurous, try looking for The Horsehead Nebula – a dark region of space where dust is blocking light from behind it.
