User Kurt Hikes

28 votes

1 answer

3k views

Why don't (or can't) stars be more than 325 or so times the mass of the sun? What limits their size?

asked Jul 24, 2020 at 20:23

21 votes

1 answer

3k views

Why doesn't dark matter clump strongly in the center of galaxies, since it doesn't feel either radiation pressure or the Pauli exclusion effect?

asked Jul 13, 2022 at 6:14

20 votes

2 answers

2k views

Why is there so little nitrogen in the Martian and Venusian atmospheres?

asked Jul 3, 2020 at 1:37

18 votes

2 answers

2k views

How can astronomers pinpoint the location of the source of a neutrino?

asked Mar 23, 2021 at 2:52

18 votes

2 answers

3k views

Why isn't most hydrogen in the universe molecular (diatomic), instead of atomic (monoatomic)?

asked Apr 8, 2021 at 7:26

17 votes

1 answer

3k views

Why do cosmologists assume that inflation began shortly after the Big Bang, rather than at the exact start?

asked Apr 20, 2023 at 1:13

17 votes

2 answers

3k views

In the onion-like elemental layers of a large mature star the neon is closer to the surface than oxygen, even though it is more massive... Why?

asked Jul 14 at 7:29

13 votes

2 answers

4k views

Why is the L3 Lagrangian point not perfectly stable? And why is the Earth-Sun L3 point a bit less than one A.U.?

asked Sep 20, 2021 at 18:47

12 votes

4 answers

6k views

How can a black hole have a charge, or be charged?

asked Jul 12, 2021 at 8:43

12 votes

2 answers

2k views

How do we know that objects that appear in duplicate or triplicate, etc. due to strong gravitational lensing aren't actually multiple objects?

asked Nov 3, 2021 at 2:02

12 votes

3 answers

2k views

Why did astronomers believe most or all stellar black holes had masses no greater than 15 solar masses?

asked Apr 18, 2021 at 15:43

10 votes

1 answer

3k views

Why is the L1 point (Lagrange) almost 1 million miles from Earth? Shouldn't it be closer to us?

asked Feb 6, 2022 at 0:13

10 votes

1 answer

3k views

Is the Sun hotter today, in terms of absolute temperature (i.e., NOT total luminosity), than it was in the distant past?

asked Jun 11, 2023 at 0:13

9 votes

2 answers

446 views

Do the neutrons in neutron stars emit the radio waves?

asked Sep 2, 2020 at 0:53

8 votes

1 answer

2k views

Why was the Cosmic Microwave Background (CMB) released at a blackbody temperature of 3000K rather than 30,000K?

asked Dec 25, 2021 at 23:38

8 votes

1 answer

1k views

Why can't 'dead' galaxies start forming stars again if they merge with another, 'active' galaxy?

asked Oct 2, 2021 at 3:59

8 votes

1 answer

932 views

Is Barnard's star an M4 red dwarf or an M0? Why is it called an M4.0V?

asked Jan 30, 2023 at 20:27

7 votes

2 answers

2k views

What are the orbital velocities of the other planets? For objects in a 'Low-Earth-Orbit' around planets other than Earth, e.g.?

asked Aug 10, 2022 at 2:07

7 votes

2 answers

2k views

How long has it been since dark energy started to reverse our slowdown and accelerate the expansion of the universe? 4 billion years ago? 4.5? 5?

asked Sep 18, 2023 at 19:48

7 votes

2 answers

778 views

Why do red dwarf (M-type) stars give off such violent flares and CMEs, out of proportion to their size and temperature?

asked Mar 9 at 0:01

7 votes

1 answer

543 views

What exactly is a 'gravastar'? How is it different from a 'regular' black hole?

asked May 27 at 12:11

7 votes

1 answer

462 views

Are red giants still primarily made of hydrogen? What is their exact composition?

asked Dec 20, 2022 at 23:38

7 votes

2 answers

1k views

Why is molecular hydrogen (H2) so difficult for astronomers to detect?

asked Sep 12, 2020 at 5:39

7 votes

1 answer

892 views

If an object 1 billion light years away emits light, does it take more than 1 billion years to reach us because of the expansion of the universe?

asked Oct 15, 2020 at 0:57

6 votes

3 answers

276 views

How do magnetic fields mess with astronomers' observations?

asked Aug 18, 2020 at 0:02

6 votes

1 answer

363 views

If a pulsar's rotational and magnetic axes were aligned and both aimed at us, would we see a steady radio source?

asked Sep 2, 2020 at 0:55

6 votes

3 answers

186 views

Do telescope measurements (in meters, usually) measure in a straight line, from edge to edge, or follow the curve of the mirror?

asked Jul 16, 2021 at 1:43

6 votes

3 answers

268 views

How do astronomers know that distant galaxies aren't actually nearby star clusters?

asked Jun 7, 2021 at 12:18

6 votes

2 answers

522 views

How do scientists know that Earth used to spin much more rapidly?

asked Aug 3, 2021 at 17:47

6 votes

1 answer

2k views

Why aren't there any large Ultraviolet (UV) space telescopes?

asked Nov 21 at 13:10

Stack Exchange Network

119 Questions

Why don't (or can't) stars be more than 325 or so times the mass of the sun? What limits their size?

Why doesn't dark matter clump strongly in the center of galaxies, since it doesn't feel either radiation pressure or the Pauli exclusion effect?

Why is there so little nitrogen in the Martian and Venusian atmospheres?

How can astronomers pinpoint the location of the source of a neutrino?

Why isn't most hydrogen in the universe molecular (diatomic), instead of atomic (monoatomic)?

Why do cosmologists assume that inflation began shortly after the Big Bang, rather than at the exact start?

In the onion-like elemental layers of a large mature star the neon is closer to the surface than oxygen, even though it is more massive... Why?

Why is the L3 Lagrangian point not perfectly stable? And why is the Earth-Sun L3 point a bit less than one A.U.?

How can a black hole have a charge, or be charged?

How do we know that objects that appear in duplicate or triplicate, etc. due to strong gravitational lensing aren't actually multiple objects?

Why did astronomers believe most or all stellar black holes had masses no greater than 15 solar masses?

Why is the L1 point (Lagrange) almost 1 million miles from Earth? Shouldn't it be closer to us?

Is the Sun hotter today, in terms of absolute temperature (i.e., NOT total luminosity), than it was in the distant past?

Do the neutrons in neutron stars emit the radio waves?

Why was the Cosmic Microwave Background (CMB) released at a blackbody temperature of 3000K rather than 30,000K?

Why can't 'dead' galaxies start forming stars again if they merge with another, 'active' galaxy?

Is Barnard's star an M4 red dwarf or an M0? Why is it called an M4.0V?

What are the orbital velocities of the other planets? For objects in a 'Low-Earth-Orbit' around planets other than Earth, e.g.?

How long has it been since dark energy started to reverse our slowdown and accelerate the expansion of the universe? 4 billion years ago? 4.5? 5?

Why do red dwarf (M-type) stars give off such violent flares and CMEs, out of proportion to their size and temperature?

What exactly is a 'gravastar'? How is it different from a 'regular' black hole?

Are red giants still primarily made of hydrogen? What is their exact composition?

Why is molecular hydrogen (H2) so difficult for astronomers to detect?

If an object 1 billion light years away emits light, does it take more than 1 billion years to reach us because of the expansion of the universe?

How do magnetic fields mess with astronomers' observations?

If a pulsar's rotational and magnetic axes were aligned and both aimed at us, would we see a steady radio source?

Do telescope measurements (in meters, usually) measure in a straight line, from edge to edge, or follow the curve of the mirror?

How do astronomers know that distant galaxies aren't actually nearby star clusters?

How do scientists know that Earth used to spin much more rapidly?

Why aren't there any large Ultraviolet (UV) space telescopes?