What observational properties of pulsars allowed astronomers to ...

[KWilfred]

What observational properties of pulsars allowed astronomers to discover them as a new type of object?
 
  What will be an ideal response?

Question 2

What were the three discoveries Galileo made with his telescope observations and quickly published into Sidereus Nuncius?
 
  What will be an ideal response?

[ally]

Answer to Question 1

A pulsar emits a very regular pattern of radiation in the radio band. The pulsation period is extremely constant and has a period between a few tenths of a second and a few seconds. Such a regular pattern of radiation was unexpected in nature, and clearly represented a new phenomenon.

Answer to Question 2

First, the moon was not perfect. It had mountains and valleys on its surface, and Galileo even used some of the mountains' shadows to calculate their height.

Second, the Milky Way was made up of myriad stars too faint to see with the unaided eye.

Third, four new planets circling Jupiter, objects known today as the Galilean moons of Jupiter.

[KWilfred]

TYSM

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Gracias!