Recently I saw an interesting Earth Venus cosmic dance video on Facebook. See the original video below or here.
Although this is not entirely accurate from physics & astronomy perspectives, the dance is a stunning example of patterns that are generated by simple things.
I wanted to recreate this cosmic dance in Excel. How else am I to get my spreadsheet fix on a Saturday?
Here is a quick demo of the final outcome. Read on to learn more about the Earth Venus cosmic dance.
The details & assumptions
To create this cosmic dance, we need a few details
- Distance from Sun to Venus & Earth – 67.2 and 93 million KM respectively
- Number of days it takes to rotate around the sun – 224.7 and 365.25 respectively
We will also assume these incorrect things to keep our model simple
- Orbits of Earth & Venus are circular with Sun at center: In reality, they are elliptical, but as these are just stretched circles, we can assume circular orbits to keep the math simple.
- Sun is static: In reality, Sun (and entire solar system) is also moving. This means, this cosmic dance may never occur.
We also need one critical detail to graph this cosmic dance:
- The angular interval for plotting the lines. In the above examples, I have used 10° (ie there will be 36 lines around the circle). This is denoted by named range m in the model. You can adjust this in the output worksheet using a form control. Different values of m yield different patterns (although most of them will be pentagonal).
The math:
Generating planetary co-ordinates:
In a table, we will generate the positions (X & Y co-ordinates) of both Venus & Earth for 3000 points in time, each incremented by m degrees, starting at 0°.
To generate the X & Y values, we will use the x=r.cos? and y=r.sin? equations (where r is the distance from Sun and ? is the angle).
Drawing the lines:
This is the tricky part. At each step in the animation our line should from one tooth of the saw tooth pattern. See this demo to understand.
For more about this technique read – interactive network chart to map relationships between people.
So during each step of the animation, we add more co-ordinates to the chart (scatter plot) to generate this saw tooth pattern. Over time, this will yield the beautiful pentagonal cosmic dance.
We can generate these successive Venus & Earth co-ordinates from the calculations performed earlier by using MOD & INDEX formulas.
Once such saw tooth line data is generated, we will designate a cell to hold current animation position. Let’s call this pos.
We will then create two named formulas – dance.x and dance.y. These will contain the data necessary for our scatter plot. We will use OFFSET formula to generate these dynamic named formulas.
The chart
Now that all the necessary calculations are done, create a scatter plot with the dance co-ordinates. Set up X & Y axis minimum and maximum values accordingly (-160 to 160 should do). This ensures that the chart remains same no matter what step of animation we are on.
Also, add 3 more series to the chart
- One for a dot to represent Venus at current position
- One for a dot to represent Earth at current position
- One for a line connecting Venus to Earth
The animation
Next, let’s add a small macro to animate the chart. This macro will increment pos from 1 to a large number. After each iteration, we will call DoEvents so Excel can re-draw the chart. That is all.
Download the Earth Venus dance workbook
Click here to download the Earth Venus cosmic dance workbook. Enable macros to enjoy the dance. Play with form control to adjust the animation speed and pattern. Examine the data tab to learn more about the calculations.
Did you enjoy the dance?
I really liked the original video on FB and that is why I recreated this in Excel. This is a great exercise to show the power of simple things generating extraordinary patterns.
What about you? Do you like this Earth Venus dance?
More Excel animation and fun:
If you like animating things, you are going to love these tutorials. Check out,
6 Responses to “Make VBA String Comparisons Case In-sensitive [Quick Tip]”
Another way to test if Target.Value equal a string constant without regard to letter casing is to use the StrCmp function...
If StrComp("yes", Target.Value, vbTextCompare) = 0 Then
' Do something
End If
That's a cool way to compare. i just converted my values to strings and used the above code to compare. worked nicely
Thanks!
In case that option just needs to be used for a single comparison, you could use
If InStr(1, "yes", Target.Value, vbTextCompare) Then
'do something
End If
as well.
Nice tip, thanks! I never even thought to think there might be an easier way.
Regarding Chronology of VB in general, the Option Compare pragma appears at the very beginning of VB, way before classes and objects arrive (with VB6 - around 2000).
Today StrComp() and InStr() function offers a more local way to compare, fully object, thus more consistent with object programming (even if VB is still interpreted).
My only question here is : "what if you want to binary compare locally with re-entering functions or concurrency (with events) ?". This will lead to a real nightmare and probably a big nasty mess to debug.
By the way, congrats for you Millions/month visits 🙂
This is nice article.
I used these examples to help my understanding. Even Instr is similar to Find but it can be case sensitive and also case insensitive.
Hope the examples below help.
Public Sub CaseSensitive2()
If InStr(1, "Look in this string", "look", vbBinaryCompare) = 0 Then
MsgBox "woops, no match"
Else
MsgBox "at least one match"
End If
End Sub
Public Sub CaseSensitive()
If InStr("Look in this string", "look") = 0 Then
MsgBox "woops, no match"
Else
MsgBox "at least one match"
End If
End Sub
Public Sub NotCaseSensitive()
'doing alot of case insensitive searching and whatnot, you can put Option Compare Text
If InStr(1, "Look in this string", "look", vbTextCompare) = 0 Then
MsgBox "woops, no match"
Else
MsgBox "at least one match"
End If
End Sub