Do Canadian astronomers use the mars rover?
No, because Canada did not fund the rovers in any way. They can use the information obtained from them, however.
If you've ever used something wireless, like a monster truck, you can imagine how. It has a strong radio signal, (VERY STRONG) and when you press a button here, it happens on Mars with the rover. Of course, you need clearance to use the rover, but I hope you don't intent to break in and use it anytime soon.
Early astronomers could see Mercury, Venus, Mars, Jupiter and Saturn. There are two factors that enabled them to see the planes -- their size and there distance. Mercury, Venus and Mars are smaller but close. Jupiter and Saturn are further away, but bigger. They could have seen Uranus too if they knew where to look but because it was fainter and further away, they missed it, and it was not until the telescope came along…