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asked What decided how the Kepler space telescope was pointed?
2d
asked How strong does a light source on the Moon have to be to be visible from Earth?
Apr
22
asked How are boulders formed on asteroids?
Apr
20
comment How come, in our lifetime, we will see the first stars which ever formed?
@RobJeffries There's only one Big Bang, and we're about to see its first light. It was surely nice to see the first jovian moon, but seeing the first star can never be outdone. Not according to our worldsview today, which maybe is what has to give here.
Apr
20
comment Circular formation around the moon
Maybe a moonbow? Even I have created faint versions of them at night in the moonlight, with a garden hose.
Apr
20
revised How come, in our lifetime, we will see the first stars which ever formed?
Changed the headline
Apr
20
asked How come, in our lifetime, we will see the first stars which ever formed?
Apr
17
answered Years, Months, Day, and Weeks?
Apr
15
asked Do neutrinos have as much information as photons do?
Apr
15
comment Wouldn't the rings of Saturn experience tidal effect?
An accessible lecture on the topic esp. second half, from year 2008.
Apr
15
comment How to differentiate between images of a gravitationally lensed object
Do you mean how the location of the source of the lensed light can be determined?
Apr
14
comment Time according to the gravity of Sagittarius A?
Great answer and very illustrating numbers about the gradual time dilatation with distance from a SMBH. Could throw in the effect for a GPS satellite there too. As for the naming issue, maybe we should call it the "A-Star Sagittarius Hole", or for short the AS... no I won't type that. I'm afraid that the next IAU meeting might buy it, though.
Apr
14
comment Can stars be observed from space by x-rays, near infrared and radio wavelengths?
In the fantastic chromoscope you can simply slide-choose what wavelength you want to see the Milky Way at. But stars are only part of what generates this. There are compact objects, gas and dust too. And even icy comets emit x-rays when the solar wind interacts with the coma.
Apr
12
answered Where to obtain Tycho Brahe's data?
Apr
12
comment Where to obtain Tycho Brahe's data?
Here is Astronomia Nova in full text for free, but I'll let you search through it :-p. Also note that Kepler recalculated all of Brahe's data before he used them! He used a different definition of the celestial coordinate system, and it might have to be recalculated again to fit with today's definitions.
Apr
12
comment Where to obtain Tycho Brahe's data?
I don't think Tycho Brahe published his data, Kepler had to convince him to share it with him and Brahe died just afterwards. Try looking for Kepler's "Astronomia Nova" in full text online, it at least contains the Mars data which Kepler used. It was translated to English first time in the 1980's, but the tables might be readable in the latin version. Here's a "study guide" if it helps. And remember the confusing date differences at that time as different countries transited in different ways from Julian to Gregorian calendar!
Apr
12
accepted What were the challenges for the ancients to observe the orbit of the Moon (instead of Mars)?
Apr
11
answered How should one rationally deal with the issue of space travelling alien civilizations?
Apr
8
comment Is there any practical use for astronomy?
Oh, someone doesn't like my argument, although it is so true that it is a truism. Few question the value of investigating or moving to different locations on the surface of the Earth. Well, the surface of the Earth is in space. When you walk you travel through space. And there's a deeper third dimension to this superficiality, undiscovered by those who never look up.
Apr
7
answered Is there any practical use for astronomy?