The main morphological types of galaxies are elliptical, spiral, and irregular.
Based on their morphology , galaxies have been classified into 3 types namely elliptical, spiral, and irregular.
These galaxies have various sizes and shapes ranging from dwarf galaxies to giant galaxies.
Elliptical Galaxy:
- The shape of it is generally circular
- These are the largest among all the types of galaxies because according to astronomers, it is formed by the merger of other small galaxies.
- Their rotational pattern is symmetric.
Spiral Galaxy:
- A spiral galaxy consists of a bright nucleus surrounded by a thin outer disk forming a spiral shape.
- This type of galaxy is the most common in our universe.
- It is divided into three classes: Spiral a, Spiral b, and Spiral c.
- Their rotational pattern has circular symmetry.
Irregular Galaxy:
- These types of galaxies have no central nucleus and irregular arms which are bluish.
- They don’t have any rotational symmetry.
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1. Frequency: 
The frequency of a light wave is given by:

where
is the speed of light
is the wavelength of the wave
In this problem, we have light with wavelength

Substituting into the equation, we find the frequency:

2. Period: 
The period of a wave is equal to the reciprocal of the frequency:

The frequency of this light wave is
(found in the previous exercise), so the period is:

Answer:Although the nervous system is very complex, nervous tissue consists of just two basic types of nerve cells: neurons and glial cells Neurons are the structural and functional units of the nervous system They transmit electrical signals, called nerve impulses. Glial cells provide support for neurons.
Explanation:
Answer:
define 1 second time
One second is the time that elapses during 9,192,631,770 (9.192631770 x 10 9 ) cycles of the radiation produced by the transition between two levels of the cesium 133 atom. ... One second is equal to 1/86,400 of a mean solar day.