This question is about our Solar System.
Which of the following bodies is at the centre of our Solar System?
Earth and Venus are planets in our Solar System. The table shows some data for these planets.
PlanetRadius of orbit in kmTime of orbit in daysVenus108 000 000225Earth150 000 000365\begin{array}{|c|c|c|} \hline \textbf{Planet} & \textbf{Radius of orbit in km} & \textbf{Time of orbit in days} \\ \hline \text{Venus} & 108\,000\,000 & 225 \\ \hline \text{Earth} & 150\,000\,000 & 365 \\ \hline \end{array}PlanetVenusEarthRadius of orbit in km108000000150000000Time of orbit in days225365Calculate the orbital speed of Venus in km / day. Give your answer to 2 significant figures.
The distance between Earth and Venus varies significantly over time (between approximately 40 million km and 260 million km). Explain why this distance is not constant.
Scientists communicate with a robotic lander on the surface of Venus using radio signals that travel at the speed of light, 300 000 km/s300\,000\text{ km/s}300000 km/s.
Show that when the planets are 120 000 000 km120\,000\,000\text{ km}120000000 km apart, it takes about 400 s for a signal to travel this distance.
A scientist on Earth sends control signals to steer the lander on Venus. The lander is programmed to move at a very low speed, limited to 0.05 m/s. Suggest why the speed of the lander is kept so low.
