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,
13 Responses to “Gantt Box Chart Tutorial & Template – Download and Try today”
Hi Chandoo
As one of your students I have followed your detailed example through with great success. However, Excel is acting in an unexpected way and I wonder if you could take a look?
http://cid-95d070c79aef808e.office.live.com/self.aspx/.Public/Gantt%20Box%20Chart.xlsm
On my version, I have to type 40239 (Which equates to 2 Mar 2010) to get the chart to display 31 May 2010 (which should be 40329)!!??
Have I done something wrong or is Excel acting up?
Thx
Oli
PS Your example file in 2007 displays correctly.
Hi,
I like this idea a lot, but I agree the name is a little drab.
As an American I may just be seeing things, but to me the combination of lines and bars on your chart looks like a bunch of cricket bats.
Maybe you could work that into a catchier name. 🙂
Cheers!
Here is some code I use to keep the axis synched.
It may be useful to some of your readers
It is based on a comment I saw on Daily Dose of Excel.
Function SynchGanttAxis(Cname, lower, upper)
'Sets the X min and X max for Category axis
Application.Volatile
On Error Resume Next
'
'Top Horizontal Axis
With ActiveSheet.Shapes(Cname).Chart.Axes(xlCategory, 1)
.MinimumScale = lower
.MaximumScale = upper
End With
'Bottom Horizontal Axis
With ActiveSheet.Shapes(Cname).Chart.Axes(xlValue, 2)
.MinimumScale = lower
.MaximumScale = upper
End With
End Function
Function SynchVerticalAxis(Cname, lower, upper)
Application.Volatile
On Error Resume Next
' Excel 2007 only
'Right hand vertical axis
With ActiveSheet.Shapes(Cname).Chart.Axes(xlValue, 1)
.MinimumScale = 0
.MaximumScale = upper
End With
End Function
@Oli.. Can you check your file again.. I see 40329...
@Dave: Even I saw things.. the bars actually looked like lollipops. How about calling this lollipop chart - now that would be yummy and goes along the tradition of naming charts after eatables (bar, pie, donut...)
@Bob: Superb stuff... thanks for sharing 🙂
Hi Chandoo
This looks really good and I think it can also be applied to show project phases / milestones.
Question: Thinking further could this be amended to display a project lifecycle (Idea through to Implementation say 7 phases) on one bar / row? Just imagine 20 projects within a programme all on one chart one bar each showing their respective lifecycle stages i.e. on one page.
Idea: As the Gantt Box Chart this is quite intensive to set up re formatting etc how about the added extra of once you have completed this to "Save as template" i.e. saves the formatting and layout of the chart as a template so you can apply to future charts. Simple to do and will save the time formatting etc again and again and again.
Therefore tip: Click on your chart demo and then click on Save As template icon (2007) - edit file name and click on save. Ready to use / apply via Templates in Change Chart Type window.
Thanks and be very interested if the lifecycle question can be resolved
Mike
How embarrassing.
I was obviously suffering from numerical dyslexia. I was one of those days.
@Mike H: You can easily make this chart to work like a generic project lifecycle plan chart. All you have to do is,
1. in a separate sheet define the steps of lifecycle and various dates in a table (with 5 columns for each of the projects you have).
2. now use a control cell to input the project name you want to show in the chart
3. based on the input, use OFFSET Formulas to get the correct data
4. Rest is same as the tutorial above
For more info on the dynamic charting visit http://chandoo.org/wp/tag/dynamic-charts/ and http://chandoo.org/wp?s=OFFSET
Your solution is really smart but in the en Excel isn't meant to do stuff like this. I, as a former PM, always thought is was frustrating that you had to do stuff like this for something simple like a Gantt chart. So I built Tom's Planner. And would like to plug it here. I think it really solves the problem you are trying to solve in the most efficient way. Check out http://www.tomsplanner.com for a free account or play around with the demo.
Hi there,
Chandoo - this is really a very nice and helpfull chart - I adopted it, so I can report a forecast or the delay of a certain task (coming from my role as an auditor for projects).
One topic I´m currently struggeling with: I do have a project lasting for lets say 12 month. For a management reporting, I want to have kind of snapshot, lets say one month back and 2 month in the future. I tried with the offset formula, but failed. Any idea?
Thx
Lopi
[...] Ein viel geliebter Klassiker ist die Erstellung von GANTT-Diagrammen mit Excel. Wir hatten das Thema wiederholt schon hier. Chandoo.org hat sich mal wieder mit einer neuen Variante hervorgetan: Das GANTT-Box-Chart. [...]
[...] [...]
Hi Chandoo - fantastic xls. One thing I can't figure out how to do is adjust the alignment of the vertical axis. I would like to left align so that I could indent to represent sub tasks. Can that be done? Or is there a better way?
I've been trying to work out if there's a way to show weekends on the graph. The closest thing I've got is to add them on a secondary axis, but then I haven't been able to keep both axis lined up together! Any ideas?
Following on from this - is it possible to show things like holidays?