Yes. Even a fairly small telescope will be adequate to reveal "the horns" of Venus. When Venus is at its maximum distance from the sun (to our perspective--not its aphelion) it will be half full. After that it either becomes crescent shaped as it swings our way, or fills out as it moves behind the sun.
a telescope
By, um, looking at it. You'll probably need a telescope, and you'll have to observe it for a considerable period of time (several months at least) to notice much of a change.
Venus is a Roman God, so, no.
to observe the solar system
Yes, with special filters.
The phases of Venus are well supported by the heliocentric system, but they are also supported very well by the previous geocentric system. All you need for Venus to have phases is that Venus should pass between Earth and Sun. That happens in both the heliocentric system and the geocentric system.
The phases of Venus are well supported by the heliocentric system, but they are also supported very well by the previous geocentric system. All you need for Venus to have phases is that Venus should pass between Earth and Sun. That happens in both the heliocentric system and the geocentric system.
That applies mainly to the inner planets: Mercury and Venus. Mars, being further from the Sun than Earth, can at most have a "three-quarter" phase, but you can't see it as a crescent, since that would require Mars to be basically between the Sun and Earth, which isn't possible. Saturn shows no phases.
According to scientists, Venus is considered one of the brightest planets that can be seen without the need for a telescope. The planet was named after the Greek goddess of love which was Aphrodite and it was discovered by the mathematician Pythagoras.
You would need a telescope with a large aperture to observe objects in space clearly. Aperture size is important for collecting enough light from distant objects. A telescope with a minimum aperture of 4 inches is recommended for observing celestial objects such as galaxies, nebulae, and star clusters.
The Earth is definitely the #1 easiest. Next in line would be Mercury, Venus, Mars, Jupiter, and Saturn. Each of those is visible without a telescope, so you'd know exactly where to point your telescope by seeing the planet with your eye first. The brightest planet that you do need a telescope to see is Uranus. So you definitely won't miss it when you're pointed at it, but you need to know where to point.
The Earth is definitely the #1 easiest. Next in line would be Venus, Mars, Jupiter, Saturn, and Mercury. Each of those is visible without a telescope, so you'd know exactly where to point your telescope by seeing the planet with your eye first. The brightest planet that you do need a telescope to see is Uranus. So you definitely won't miss it when you're pointed at it, but you need to know where to point.