because of your mom
Scientists do not observe Mercury as often because it is difficult to do so.
they move because of space eruptions
telescope
It is difficult to get to the planets to observe them closely. Much of life (bacteria) would only be observable under a microscope, and even the largest living beings known on Earth wouldn't be observable from a telescope from Earth, for example.
opposition
Pluto is difficult to observe astronomically, because it is both very far away, and relatively small, so people can't get information.
Astronomers cannot locate extrasolar planets with telescopes because these planets are outside of our solar system and too far away for telescopes to directly observe. Instead, astronomers use indirect methods such as radial velocity and transit techniques to detect these distant planets.
They used a telescope
The planets around the sun are not visible to the naked eye because they are much smaller and dimmer than the sun, making them difficult to see against the sun's bright light. Additionally, the glare from the sun can make it challenging to distinguish the planets in the sky. Astronomers use telescopes and other tools to observe and study the planets in our solar system.
light from the they orbit makes it difficult to locate extrasolar planets with telescope
Impossible to observe: bacteria, viruses, molecules, atoms, and at the other end of the size continuum, mountains, landforms, planets, etc.Very Difficult: human eggs, large single cells of other kindsRather Difficult: crystals of many organic chemicals, fine details of fibers and papers, insect eyes and many others
There is no definitive answer to how many infinite planets there are in the universe. The universe is vast and constantly expanding, with potentially countless planets beyond what we can currently observe.