ive got 2 questions:
the star Vega is 25 lightyears away from us. if we sent a radio message to Vega, and another civilization on a planet circling that star answered us, in what year could we expect to hear a reply?
why was it necessary to make radio telescopes so much bigger than optical telescopes?
i looked in my textbook but i couldn't find the answer
distance=veloctiy *time
50lightyears= 1lightyear/year * time
time= 50 years. Duh.
radio telescopes have to collect enough energy to overcome the energy in background radiation, so radio telescopes are big.
Sure! I'll be happy to help you with your questions.
1. To determine in what year we could expect to hear a reply from Vega, we need to consider the distance between us and the star. You mentioned that Vega is 25 light-years away from us. This means that light, including radio waves, takes 25 years to travel from Vega to Earth.
Assuming that the signal we send reaches Vega instantaneously, it will take another 25 years for the reply to travel back to us. Hence, the total time for the radio message to be sent and the reply to be received would be 25 years + 25 years = 50 years. Therefore, we could expect to hear a reply approximately 50 years after we send the radio message.
2. Radio telescopes are generally larger than optical telescopes for a few reasons:
a) Wavelength: The major difference between radio waves and visible light is their wavelength. Radio waves have much longer wavelengths, which means they require larger antennas or dish sizes to capture them effectively. This is because the size of the antenna or dish needs to be comparable to the wavelength of the waves being observed. On the other hand, visible light wavelengths are much smaller, allowing optical telescopes to have smaller apertures.
b) Interference: Another reason for the larger size of radio telescopes is to minimize interference from sources on Earth. Buildings, power lines, and other human-made structures can generate radio frequency interference (RFI). By having large dishes or arrays, radio telescopes can better filter out this unwanted RFI and capture faint astronomical signals.
c) Sensitivity: Larger dishes or arrays in radio telescopes allow for higher sensitivity in detecting weak radio signals from distant astronomical sources. Since radio waves from space are generally much weaker than visible light, larger collecting areas are needed to gather enough signal to overcome background noise and provide clear observations.
In summary, the need for larger sizes in radio telescopes is mainly due to capturing longer wavelength signals, mitigating interference, and improving sensitivity to detect weak signals from the depths of space.
If you couldn't find the answers in your textbook, it's always a good idea to consult additional resources such as reliable websites, scientific journals, or consult with a subject matter expert for further clarification.