You’ve found your way around the Big Dipper and the major constellations, and are ready to find some fainter celestial objects. The problem is – you don’t know where to start, or you’ve had a go and just can’t find that galaxy you were after.
What you need is to learn the technique of star hopping.
It’s a vital tool for the backyard astronomer and we’re going to explain how to star hop and why it’s so useful for us.
What is Star Hopping?
Star hopping is pretty much how it sounds. We find a difficult target by starting with a recognisable star and 'hopping' from it to other stars until we reach it.
Like stepping stones across a river, astronomers navigate the inky blackness of space by hopping from one star to star until arriving at the object we're after.
The best way to start learning star hopping is to use easily recognisable constellations, such as the Big Dipper or the Orion. Use these as your stepping stones, and expand from those as you gain confidence.
Success with this technique comes from planning a hopping route in the day before giving it a go in the evening.
How Useful is Star Hopping to Backyard Astronomy?
In a word: very!
Finding faint objects can be difficult even if you’ve set up your equatorial mount perfectly and can dial in the coordinates.
If you have an altaz mount, being able to star hop is even more useful.
Star hopping makes it so much easier to find the object you’ve never seen before by using ones that you do recognise. This saves so much time and wasted effort, you’ll wonder why you haven’t done it before!
The only astronomers that don’t need star hopping skills are those with go-to scopes. Even then, it’s a helpful skill to have… just in case.
What Equipment Do I Need for Star Hopping?
What Equipment do I Need for Star Hopping?
Thankfully, you don't need much more than you already have. A pair of binoculars, a telescope with a finderscope and a star map or night sky software will set you on your way.
Below are the steps we recommend to get from novice to expert starhopper...
A wider field of view is the secret to success for star hopping.
To get some simple practice in, start with binoculars. They have a wider field of view than a telescope and there is no image inversion. This makes it easier to see more of the sky and move in the right direction for each hop.
The downside of bin’s though is star hopping is tough to achieve if you don’t have a steady mount. Handheld binoculars only deliver good results from a star hopping trail when you’re using bright and easy to recognise objects along the route.
They also suffer from low magnification compared to your scope. There are very few deep space objects you’re going to find and enjoy with binoculars!
Progressing to your Telescope
When you’re ready to move to a telescope for star hopping, the finderscope is your key piece of equipment. The finderscope has a much larger field of view than your telescope (a decent 8x50 finderscope - like this one on Amazon - may cover 5° of sky, compared to 0.5° with a low powered eyepiece).
Unlike your binoculars, the finderscope will invert the image, so up is down and vice versa.
This is one reason why the best kind of finderscope for star hopping is a Telrad.
Telrads have no magnification but do superimpose dimly lit concentric circles on your view of the night sky. The circles show you which stars are 1°, 2° or 4° away from where you are looking.
Because there is no magnification, there is no image inversion. When you use a Telrad on your telescope, up is up and down is down!
Inside the Eyepiece
When your star hopping approaches your target, the last step or two will probably be too faint and small for your finderscope to deal with. At this point, you’ll complete star hops in the eyepiece of your scope.
To increase your chance of success use a low magnification eyepiece to provide a decent field of view.
When planning your star hops, the last hop or two can be with fainter stars, which you’ll see in the eyepiece. But, they have to be closer together - as your field of view may only be a tenth what it was in the finderscope.
How Do I Get the Most Out of My Telescope?
The best advice we can give you is to learn to use your finderscope.
Make sure to align it with your scope as you’ll be using it a whole lot more than the scope itself for star hopping.
Think of it this way – looking through the finderscope is like looking through a straw, while the eyepiece is like trying to see through the eye of a needle.
It’s because we can see so much more of the sky through the finderscope that makes it the best piece of equipment for star hopping.
You are going to position the eye of the needle using a series of hops or jumps. Each jump needs to be within the same field of view. So, if you have a 4° field of view you can plan a hop which takes you no more than 4° from the starting star.
Telrad scopes have three concentric circles in them which show various fields of view: 0.5°, 2° and 4°.
As you get closer and closer to your target, the hops may become shorter and use fainter objects.
As you become more demanding, the hops will become more challenging. Eventually, your hops will take place within the view of your telescope’s eyepiece.
At this point it helps to know the field of view size of your telescope eyepiece because hops need to start and finish within it.
For example, you will move from the left side of your view through the eyepiece to the right side of your view through the eyepiece.
What you shouldn't do is pick a hop that takes you outside of the field of view i.e. one where you can only see either the starting point or the end point within the field of view. Doing this leaves you at risk of getting disoriented and losing the path completely.
The widest fields of view come from the lowest magnification eyepieces, so start your hunt using one of those.
How Should I Start Star Hopping?
Planning is the best place to start star hopping.
When you’ve selected the object you want to find (click here to sign up for our weekly email giving you targets to look for) you need to plan your route there, starting from an easily recognisable star.
The Pocket Sky Atlas has the Telrad ‘bullseye’ printed in it, making it ideal to use for planning.
Steps to Star Hopping
These are the steps you should follow to achieve great results using star hopping
- Pick a target that you want to find
- Create a transparence with different fields of view drawn on it. You can trace them from inside the cover of The Pocket Sky Atlas (see picture)
- Make sure to include a field of view circle that matches that of your lowest magnification eyepiece
- Mark on your map the route you plan to take from your start position to the target
- Out in the field, use your notes to hop from an obvious starting position, like Orion's Belt, the Big Dipper or Arcturus.
- Now, retrace the directions from your map, making sure to compensate for inverted images, e.g. 'up' on your map may be 'down' in your finderscope.
- If you get lost, just go back to the beginning and try again
- Still lost? This does happen and it's best to review these in the warmth and light of home. Did you set a hop that was too away, move in the wrong direction, use stars that are too faint? Clean up your notes and have another go tomorrow.
There are other ways you can plan your star hopping routes that don't involve a paper map.
Here are links that share with you the detail you need to go down these routes
Things to be Aware of When Star Hopping
Make sure you know how well you can see from your site. You need to know which are the faintest stars visible to you otherwise you risk using choosing a hopping star which you just can’t see.
The Bortle scale indicates the level of light pollution for your area and tells you how likely it is to see a celestial object from where you’re standing.
To check how accurate it is, use your star atlas to learn at what point stars become invisible to you through your finderscope. Start with magnitude zero, 1, 2, etc, until you can’t reliably see any more.
Start with Vega (magnitude 0.03), which is the second-brightest star in the northern night sky, right after Sirius. By comparison, Polaris (aka the North Star in the Ursa Minor/Little Dipper constellation) has an apparent magnitude of 1.97.
If your limit is magnitude 4, you’ve learned not to include any magnitude 5 or above stars for star hopping, because you just won’t see them!
You also need to know what size field of view you are working with. The easiest way is to search Google for your eyepiece/finderscope make and model and get the details from the manufacturer.
You can also use them in your telescope and centre on a well-known star field, such as the Orion Nebula. Compare how much you can see through your eyepiece to the maps you have and work out from them an approximation of your field of view.
As a last resort, a good rule of thumb for fields of view are 5° for your finderscope and around half a degree for a low magnification eyepiece.
The last thing you should be aware of is the effect of optics on your view of the stars.
You may have an inverted view or an upside down view. When you are actually standing at your telescope star hopping, you need to remember to move your scope in the right direction. Sometimes up means down and left means right… and with so many points of white light, it is not always easy to tell!
Practice Makes Perfect
To get comfortable with star hopping, there is no substitute for just getting started.
At the beginning just keep it simple, build your confidence with some simple challenges. Many backyard astronomers start with either the Big Dipper or Orion, and we suggest you do the same.
As you become better at planning your hops, try and branch out into some that are more challenging. The first time you try to navigate a star field you don’t recognise will be tricky.
Remember, you will likely see more stars in your eyepiece that there are published in the star atlas. This is because the atlas only shows stars to magnitude 7, whereas you eyepiece will show you stars fainter than that. Part of the trickiness in the technique is recognising the stars from the map in your eyepiece, especially if the field is inverted.
Further Star Hopping Info
Although star hopping is a very simple idea, it can be tough to crack when you move into more complex searches. We share with you below some links that will help you move on from this starter article and improve your object finding skills.
- This example from the Cloudy Nights forum shows you exactly the kind of thing we describe in the ‘how to’ section, above.
- If you're more of a visual type, then this great YouTube series of over 50 videos on star hopping could be just the thing you need
- If you are more of a reader try: Garfinkle’s Star-Hopping: Your Visa to Viewing the Universe, or
- The much cheaper MacRobert’s Star-Hopping for Backyard Astronomers
If you have any questions about star hopping or think we missed something and would like to see it added, feel free to drop a line telling us so. Email email@example.com
Written by Adish War
Product images sourced from Amazon.com