The galaxy is extremely large. It is elliptical in shape, and measures roughly 80,000 light years on its short axis and 200,000 light years on its long axis. Even a single light year (the distance light travels in a year) is a very long distance, approximately seven trillion miles. The only way we have of investigating the galaxy at large is by telescope, and even the best telescopes can only see so much. When you are looking at something that is on the order of quadrillions of miles away, it is really hard to see. That is why it is difficult to find Earth-like planets elsewhere in the galaxy.
The closest galaxy that has planets is the Andromeda galaxy. It is the nearest galactic neighbor to the earth. The Milky Way has other planets too.
In our solar system, the inner four planets, Mercury, Venus, Earth, and Mars, are referred to as rocky, or terrestrial ("Earth-like"). Outside the solar system it is estimated as many as 40 billion planets in our galaxy alone would be similar to Earth.
In our own solar system, the planet whose density and internal structure most resemble that of the Earth is Venus. There may be other planets elsewhere in the galaxy which resemble Earth even more closely, but we have not had the opportunity to observe them.
The Sun, all its planets and the galaxy in which the Sun sits all rotate.
There are more than 10 billion trillion Earth-like planets (100 billion+ per galaxy/1 or 2 per star) in the universe, and estimates may vary.
Earth
earth
Compared to some other planets in the same galaxy, yes; it is actually fractions of the size of other planets in this galaxy
The closest galaxy that has planets is the Andromeda galaxy. It is the nearest galactic neighbor to the earth. The Milky Way has other planets too.
IR as in infrared? Who says it is "critical"? Search for life elsewhere in the Galaxy, or here on Earth?
Mars and Earth are planets in a galaxy called the Milky Way, inside the universe.
well earth
There are eight planets, including Earth, in our solar system, there are many solar systems in our galaxy, and there are countless galaxies in the universe.
No. Earth is the 5th largest of the eight planets in the solar system. There are many more planets in the galaxy in other solar systems with numbers estimated in the hundreds of billions. Many that we know of are larger than Earth while some are smaller.
...only as a metaphor. The Earth is a planet that is in the Milky Way galaxy. The Earth is not a galaxy. No, the Earth is a planet which orbits the Sun (which is a star) along with several other plants, this is called the solar system. Our Sun and its planets along with millions of other stars form a galaxy called The Milky Way.
Nothing from another galaxy can affect Earth ever. Other galaxies are too far away.
In our solar system, the inner four planets, Mercury, Venus, Earth, and Mars, are referred to as rocky, or terrestrial ("Earth-like"). Outside the solar system it is estimated as many as 40 billion planets in our galaxy alone would be similar to Earth.