**Tell us what’s happening:**

Hello,

So I am having trouble understanding the formula to obtain the values of time orbitals. So far I have mapped the array of objects to extract the average altitude data and was looking to map again using the formula, however the values are not as they should be.

I presume the formula I am using is incorrect but I am not sure.

Thanks.

**Your code so far**

```
function orbitalPeriod(arr) {
var GM = 398600.4418;
var earthRadius = 6367.4447;
let results = arr.map(function(e) {
return e.avgAlt;
})
let orbitalPeriods = results.map(function (e) {
return 2 * Math.PI * Math.sqrt((earthRadius + e)/ GM)
})
console.log(orbitalPeriods)
}
orbitalPeriod([{name: "iss", avgAlt: 413.6}, {name: "hubble", avgAlt: 556.7}, {name: "moon", avgAlt: 378632.553}]);
```

**Your browser information:**

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.

**Challenge:** Map the Debris

**Link to the challenge:**