# Instructions append

For the Python track, this exercise asks you to create a `SpaceAge` _class_ (_[concept:python/classes]()_) that includes methods for all the planets of the solar system.
Methods should follow the naming convention `on_<planet name>`.

Each method should `return` the age (_"on" that planet_) in years, rounded to two decimal places:

```python
#creating an instance with one billion seconds, and calling .on_earth().
>>> SpaceAge(1000000000).on_earth()

#This is one billion seconds on Earth in years
31.69
```

For more information on constructing and using classes, see:

-   [**A First Look at Classes**][first look at classes] from the Python documentation.
-   [**A Word About names and Objects**][names and objects] from the Python documentation.
-   [**Objects, values, and types**][objects, values and types] in the Python data model documentation.
-   [**What is a Class?**][what is a class] from Trey Hunners Python Morsels website.

[first look at classes]: https://docs.python.org/3/tutorial/classes.html#a-first-look-at-classes
[names and objects]: https://docs.python.org/3/tutorial/classes.html#a-word-about-names-and-objects
[objects, values and types]: https://docs.python.org/3/reference/datamodel.html#objects-values-and-types
[what is a class]: https://www.pythonmorsels.com/what-is-a-class/
