Theory:

    “Look, it’s up to something, Daddy,” Tilloo suddenly noted some movement in the spacecraft. Others in the Control Room saw it too. All eyes were now glued to the screen.

    A mechanical hand was emerging from the spacecraft. It was approaching the surface of the planet. It bent and touched the soil. What was it up to? People crowded towards the screen for a closer look. The telescopic lens of the TV camera zoomed in to the tip of the mechanical hand.

    Tilloo was staring at the control panel and its attractive buttons. An irresistible desire got hold of him to press the most prominent of all buttons, the red one. He moved...
Explanation:
 
After noticing the coloured panel, Tilloo saw something suddenly moving in the spacecraft, and so he asked his father to look at that. On the other hand, the other persons in the Control Room also noticed the movement in the spacecraft. Everyone in the Control Room looked at the screen.

While they looked at the screen, a mechanical hand arose from the spacecraft, and it started to approach the planet's surface. Moreover, it bent and touched the soil. People were astonished to see the things displayed on the screen. They were unaware of what was happening around the surface of the planet. In addition, the telescopic lens of the TV camera zoomed into the tip of the mechanical hand. It was done because to know what the alien robotic hand was doing.

While everyone was looking at the screen, Tilloo looked at the control panel and its attractive buttons. The attractive switches and panels captured his interest. In addition to looking at the attractive panels, he was interested in touching the red coloured button. Among all the controls, he had an irresistible desire to press the red one. Tilloo probably pressed the red button due to the attractiveness of the colour, or else, among all the colours, the red seemed to be dominating one. Later Tilloo moved closer to it.
 
Meanings of the difficult words:
 
S.No
Words
Meanings
1
GlueBe paying very close attention to something, especially a television or computer screen
2
Emerging Becoming apparent or prominent
3
Prominent Very well known and important
4
IrresistibleImpossible to refuse, oppose, or avoid because it is too pleasant, attractive, or strong
Reference:
National Council of Educational Research and Training (2007). Supplementary. An Alien Hand - Jayant Narlikar (66-73). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.