We know that intergalactic travel is possible in the Animorphs universe. As Ax says:
A massive force of human-Controllers will enable [the Yeerks] to effectively push out into other galaxies.
#52 The Sacrifice, p. 4. Emphasis mine.
Regardless of this, though, I had always assumed that most species from Animorphs were from the Milky Way. Until I read of the Ellimist's first visit to the Andalite homeworld:
I flew for a long time, longer than I had ever stayed in Zero-space before. I emerged finally at a far edge of the galaxy, billions of light-years from the populated core of old systems and old planets.
The Ellimist Chronicles, p. 84. Emphasis mine.
So the Galaxy the Andalites are from is billions of light-years wide.
If this is correct, the Andalites cannot be from the Milky Way. The Milky Way is (at the highest current estimates) 160.000 light-years in diameter. Thus, the Andalites' galaxy is thousands of times larger than the Milky Way. It is also larger than any galaxy presently known to humans (out of universe.)
But I always thought The Andalites were from the Milky Way. Here are some possibilities:
- The Andalites are from another galaxy.
- Applegate didn't know about the size of the Milky Way, and made a mistake.
- The Milky Way is larger in the Animorphs universe than what (real-world) scientists believe it is.
Perhaps relevant to #2, Applegate has stated:
Hah! This is one of my favorite things when someone asks about the science. Because here's what you need to bear in mind: between us we have one BA in English and one GED. When it comes to science we are dumb and dumber.