a. They reported that it had a reddish color and could be seen during the day.
b. They reported that it was in the Taurus constellation.
c. They reported that it had a yellowish color.
d. They reported seeing it during the summer months.How do we know that the “guest star” reported by Chinese astronomers in 1054 AD was a supernova?Two reasons, actually. One is that it was very bright, visible even during the day. Only a supernova event would have this characteristic. The other indication is that we have found a supernova remnant (known as the Crab Nebula) in the same place in the sky where that supernova was reported in medieval times. None of the answers you've provided seem to be entirely accurate, although I would be inclined to pick A.How do we know that the “guest star” reported by Chinese astronomers in 1054 AD was a supernova?The real answer is that we found a supernova remnant in the location they described.
We measured how fast the remnant is expanding (Doppler shift to measure the radial speed directly, precise angular measurement to find out the "arc-seconds per year" expansion.
We then calculated how far back the size would have been zero and it matches quite well with the year 1054.
They did report that it could be seen during the day (for over 3 weeks), which would make it bright enough to have been a supernova.
However, seeing something during the day is not -- by itself -- an indication that something is a supernova. We can easily see the Sun during the day. We can see the Moon. Some of us can see Venus when it is at its brightest. I have some friends who can sometimes see Jupiter during daylight (I never did).How do we know that the “guest star” reported by Chinese astronomers in 1054 AD was a supernova?none of the above, really.
the historical reports are consistent with a supernova.
additionally, we have found a supernova remnant of the correct age (the crab nebula) in the correct part of the sky (taurus).
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