Which of the following statement is incorrect about Julian day?

Julian day is more useful for people resident on the Earth

The number of days between two events is found by simply subtracting the Julian day of one from that of the other

The Julian day count is uniform and continuous and does not involve leap years or different numbers of days in different months

The Julian day begins at noon rather than at midnight so that astronomers observing the heavens at night would not have to deal with a change of date during their watch

Correct Answer : Julian day is more useful for people resident on the Earth

Explanation : The Julian day is mainly used by the astronauts and astronomers dealing with outer space to keep track of time. In these cases, the universal time is taken as a reference. People living on the surface of the earth prefer other time systems like the Universal time or the Local time.

Recently Updated in Spaceflight Mechanics Questions

What are the disadvantages of the optical sensors?

They are not efficient

Weather must be favorable

They are not accurate

Satellite must be in darkness

Correct Answer : Option (B) : Weather must be favorable

Explanation : The optical sensors are very accurate in determining the satellite. For taking a good photo, there are some conditions that have to be followed- good weather conditions, correct lighting and the satellite must be in the sunlight.

Which of these devices is used to observe objects by having two or more antennas with high aperture?

Telescope

Hyper telescope

Radio interferometer

Optical Interferometer

Correct Answer : Option (C) : Radio interferometer

Explanation : Radio interferometers are sensors which accurately measure the directional information of a satellite using radio interferometry. It makes use of 2 or more antennas of high aperture and waves interferes on the same receiver. This is similar to the double- slit experiment phenomenon.

Which of these radars operate by identifying signature od a booster by disturbance in ionosphere?

Pulse radar

Surface radar

Continuous wave radar

Over- the- horizon radar

Correct Answer : Option (D) : Over- the- horizon radar

Explanation : OTH radar operates on the principle of detecting launches and identifying the signature of a particular booster by the disturbance it causes in the ionosphere.