Cosmic or interstellar dust corresponds to reduced size carbon fragments or silicates that can only be visualized using the microscope, these do not exceed one micron (thousandth part of a millimeter) in diameter, its shape is irregular, therefore it is called grain interstellar.
It is possible to define cosmic dust as a contiguous of matter and radiation that occupies the gaps of interstellar space.
In the interstellar medium the temperature fluctuates according to the establishment of hot sources that are present in the place, on the other hand, there are extremely cold areas. Much of the interstellar matter (99%) is composed of gases, of which 90% is composed of hydrogen atomic or molecular, including approximately 9% helium and 1% other heavier components compared to the latter element.
By Eduardo de Freitas
Graduated in Geography
Brazil School Team
Source: Brazil School - https://brasilescola.uol.com.br/geografia/poeira-cosmica.htm