If you’ve recently purchased a Telescope, or are looking to get one, then a common question by new astronomers is whether you can use a telescope during the day.
You may be wondering if it is possible if it is worth your time or even if it is safe.
When I first started getting into Astronomy I always thought that I had to use my Telescope at night. To test this assumption, I did some research and then testing to find out if I was right.
So, can you use a telescope during the day? You can use a telescope during the day. However, there are some factors to consider and limitations that will dictate what, how and when you can see objects in the sky through your scope. For instance, you will need to avoid the sun at all costs as this can damage your eyes.
Factors To Consider
Now, before we look at some of the objects that you will be able to see, identify and observe, it is important to take into consideration a number of factors.
For one, it depends on the specifications of your telescope. Aperture, Focal Length, Magnification, Focal Ratio and Resolving Power are all components of a telescope that dictate its ability to portray images of the objects in the sky.
The performance of your telescope ultimately dictates what you are able to see. Whether it is night-time or not.
Secondly, it is important to consider your location and where you are using your telescope. If you are in a cloudy area (or one with a lot of pollution) your views may be very restricted, or limited. To get the best results from your telescope it is always best to observe from rural areas and/or when the weather conditions do not impact on your viewing.
What Can You See Through A Telescope During the Daytime
Astronomy does not have to be left until the cease of day. The best times for day viewing will always be when there is a clear sky. You want to always look for the highest point of the sky. The darker the blue at this point, the better your chances will be.
Now caveats aside, all five of the classical planets, major bright stars and significant satellites are visible through a moderate-spec telescope.
Using my Meade Infinity 102 MM AZ Refractor, I’ve seen all of the planets (including Mercury, Venus and Jupiter) alongside stars like Vega, Castor, Capella and Arcturus. Beyond this I have even observed the Jovian satellites when the daytime conditions have been clear.
I document below what you can expect to see during the day with your telescope and some observations made. I’ll start with some of the easier objects to identify and then move on to the more difficult.
The Moon is one of, if not, the easiest objects to observe during the day. It is commonly available to see, but there will be sometimes (like when it is a full moon) that you will be able to observe more.
You will notice that you cannot see the Moon with as much clarity and detail during the day (when compared to at night). Nonetheless, it is still possible and fascinating to view.
When viewing the moon, one of the most interesting areas to view is known as “The Terminator”. This is the line that falls in between the day and night parts of the Moon.
Mercury is one of the easiest planets to see. Don’t take my word for it – daylight was the preferred time for professional astronomers to observe the planet throughout history.
I’ve been able to view Mercury within only about a degree from the solar limb and it is fairly easy to see. You can also get quite a sharp view of the planet and its environment.
You’ll notice that Mercury is always close to the sun, so it will not stand out as much as it would during the night hours.
Venus is another planet that will be easy to see.
Sometimes, if the conditions are right it can be observed with the naked eye (If the skies overhead are are very clear). Failing these conditions, unless it is particularly congested, you should still be able to observe it through your scope. High altitude skies are probably are best.
Like Mercury, Venus appears close to the sun, so it will appear more faintly than at a latter hour.
Jupiter is one of the more difficult planets to see. You will notice that when viewing Jupiter the contrast tends to be weak and it appears relatively faint when viewed during the height of the day.
As such, it is advised to observe Jupiter towards the end of the day just before the sun starts to set. Interestingly, this is probably the best time you could observe it; in complete darkness I have found that the planet shines too brightly so that I lose a lot of the detail. This is where colored filters come in, but I am yet to test them during this time.
If you get your timings right, it may be possible to see the moons of Jupiter. I’ve managed to locate them and observe them on a couple of occasions.
Saturn is another planet that is fairly difficult to see and you need the right conditions for it to be possible. How clear and bright the sky is will be the fundamental factor influencing your chances. Depending on the conditions, Saturn can range from looking faint to completely invisible.
I have found that if Saturn is within roughly 20 degrees of the Sun that it cannot be observed at all.
Using polarizing filters is another way you can improve visibility of this planet!
Mars is one of those planets that sometimes you can see, other-times you cant. It varies enormously. I have noticed that it can be either very challenging or a lot easier (like Mercury). As usual, it depends on other factors than just the location of the planet itself.
What I have found is that Mars is great to see through a telescope about an hour before sunset and/or after sunrise. You need to look at a time when the atmosphere has not had time to heat too much.
The brightest stars are normally visible throughout the day. The brightest star, Sirius, (not including the Sun) is one of the best to look out for. Beyond this Arcturus, Rigel, and Betegeuse are all stars that can be located through your scope in the daylight.
What Not To Look At
While it may be tempting, you should never look directly at the sun through your telescope. Looking at the sun with your eyes is damaging and painful, now imagine that on a greater scale.
Looking at the sun through a telescope will really damage your eyes and can cause long-term implications to your vision.
However, the only time this doesn’t apply is if you have the specialist equipment. If you have a full aperture solar filter, then it will be possible to observe the sun and not cause damage to your eyes and eyesight.
It is actually advisable to get one of these ahead of any daytime astronomy. This way, you will be completely protected from the dangers of the sun, even if you accidentally look directly at it (easily done).
Thankfully, if this sounds like its something you want to do, full aperture solar filters are available for purchase as an individual piece that fit on the end of nearly every telescope.
By using this device, you can expand what you can see in the day with your scope, and start to observe one of the universes most impressive phenomena.
How To Find Objects During The Day
One of the best ways to prepare for daytime viewing is to plan ahead. It is useful to familiarize yourself with the sky and planet positions at night before you try to find them in the daytime. It helps to use their location against the Sun for reference. The Sun is the largest point of reference in the sky during the daytime.
Now that you have your list of objects to observe, here’s the best way to go about seeing them.
Unless you are using a full aperture solar filter, cover the end of your telescope. Begin by facing the Sun, and move slowly away from it.
Then you are going to want to stop just before you reach the point where you believe the planet to be. Now, uncover your scope and direct toward the planet while moving away from the Sun.
Do not ever direct back to face the Sun while you’re looking through your scope.
It also helps to have a family member of friend with you who can prevent you from directing back into the trajectory of the sun through your Telescope.