# Let There Be Light explainer

The aim of this puzzle: Set the radius of the `sun` to 20.

Walkthrough of the solution: The `sun` object is an SVG circle. The size of a circle is determined by its radius. To set the radius, you use `'r'` as the 1st argument of the `.attr()` call. The 2nd argument will be the new value of the radius which should be 20.

Sample code solution:
(Tap below to reveal)

``````sun.attr('r', 20);
``````

D3 Concepts: `.attr(r,)`
Additional Code (hidden code that runs before the puzzle’s code):

``````const xx = window.innerWidth/2;
const yy = window.innerHeight/2;
const planets = [
'mercury',
'venus',
'earth',
'mars',
'jupiter',
'saturn',
'uranus',
'neptune'
];
const offset = {
sun: 0,
mercury: 57,
venus: 108,
earth: 149,
mars: 228,
jupiter: 780,
saturn: 1437,
uranus: 2871,
neptune: 4530
};

sun: 864,
mercury: 3,
venus: 7.5,
earth: 7.9,
mars: 4.2,
jupiter: 88.8,
saturn: 74.9,
uranus: 31.7,
neptune: 30.779
};
const colors = {
sun: '#F3700D',
mercury: '#868686',
venus: '#D5C9AA',
earth: '#374253',
mars: '#8E543E',
jupiter: '#C0A476',
saturn: '#B29D71',
uranus: '#B2D6EB',
neptune: '#3C5BE9'
};

let solarSystem = svg.append('g');
for (let item of planets) {
let rot = `rotate(\${pickRandom(360)},\${xx},\${yy})`;
let off = 20 + offset[item]**0.52;
let planet = solarSystem.append('circle')
.attr('fill',colors[item])
.attr('cx',xx)
.attr('cy',yy-off)
.attr('transform',rot);
let trail = solarSystem.append('path')
.attr('stroke',colors[item])
.attr('stroke-width',1)
.attr('fill','none')
.attr('d',
d3.arc()