Ask an Astronomer Team

Dave Rothstein

Dave is a former graduate student and postdoctoral researcher at Cornell who used infrared and X-ray observations and theoretical computer models to study accreting black holes in our Galaxy. He also did most of the development for the former version of the site.

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Title Created Date Hits
When measuring the expansion of the universe, do astronomers consider that they're seeing how galaxies moved long ago, not today? (Intermediate) Jan 08 59157
How long would it take the Earth to fall into the Sun? (Intermediate) Jul 05 138497
Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (Intermediate) May 05 51942
Why are accretion disks flat? (Intermediate) Apr 05 59169
How do we know that nuclear fusion is still going on in the Sun? (Intermediate) Jan 05 84700
Is the universe really like an expanding balloon? (Intermediate) Jan 05 86051
If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (Intermediate) Dec 04 174615
How can we understand the meaning of large numbers like "a million million?" (Beginner) Nov 04 46783
Would extraterrestrial civilizations know that there is life on Earth? (Beginner) Oct 03 51910
Will the Moon be invisible in 500 million years? (Beginner) Oct 03 69664
What is apparent magnitude? (Intermediate) Sep 03 135018
Is the universe expanding faster than the speed of light? (Intermediate) Sep 03 509157
How do we define distance in an expanding universe? (Intermediate) Aug 03 94433
When the Sun converts mass to energy, do the orbits of the planets change? (Advanced) Aug 03 124579
What is the observational difference between a star and a planet? (Beginner) Jul 03 303903
How long do supernova remnants last? (Intermediate) May 03 55512
What is the universe expanding into? (Intermediate) Apr 03 630641
How can we see galaxies if their stars are so faint? (Intermediate) Feb 03 55319
Does gravity vary across the surface of the Earth? (Intermediate) Feb 03 286410
What process would bring about a quark star? (Intermediate) Jan 03 51441
Could there be life in the galaxies nearest to the Milky Way? (Intermediate) Jan 03 142634
Does evolution contradict the second law of thermodynamics? (Intermediate) Jan 03 217242
How does the brightness of a star depend on its distance from us? (Beginner) Dec 02 97121
How do astronauts communicate with their families from space? (Beginner) Dec 02 84573
Can you see the future as you fall into a black hole? (Intermediate) Dec 02 119703
How can we see the Milky Way if we are inside it? (Intermediate) Dec 02 391165
When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (Intermediate) Dec 02 70985
Why do astronauts in space need to exercise? (Beginner) Nov 02 56712
Why doesn't the length of each day change much around the solstices? (Intermediate) Nov 02 97879
Do we see the same stars from above and below the equator? (Beginner) Nov 02 142287
Why isn't the sky bright at night if the universe has so many stars? (Intermediate) Nov 02 237360
What are "blue stragglers" in globular clusters? (Intermediate) Nov 02 75049
How do you calculate the lifetime of the Sun? (Advanced) Nov 02 186267
How long does a solar eclipse last? (Beginner) Oct 02 171761
What companies or businesses can astronomers work for? (Beginner) Oct 02 78458
Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (Advanced) Oct 02 47347
What is the farthest in space that we have gone? (Beginner) Oct 02 143306
How close does a supernova need to be to damage the Earth's environment? (Intermediate) Sep 02 55940
Is light of different colors affected differently by gravity? (Intermediate) May 02 49941
Why do clocks turn in the opposite direction from the Earth and Moon? (Intermediate) Apr 02 97502
Do most astronomers believe in God based on the available scientific evidence? (Beginner) Mar 02 138538
What can we learn from the color of a star? (Intermediate) Mar 02 195469
What happens to a substance if its speed is more than the speed of light? (Intermediate) Mar 02 156095
Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (Intermediate) Feb 02 100313
Could there have been multiple Big Bangs at different places in the universe? (Intermediate) Feb 02 74341
What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (Advanced) Feb 02 107121
How do astronauts use math in their jobs? (Beginner) Feb 02 99369
How does astronomy benefit humankind? (Beginner) Dec 01 133458
What is the physical difference between a star and a planet? (Intermediate) Sep 01 410145
Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (Advanced) Aug 01 51277
Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (Advanced) Aug 01 44425
What does the term "visible universe" mean? (Beginner) Jul 01 58130
How do astronomers use math in their jobs? (Beginner) May 01 184525
What is the density of a black hole? (Advanced) Apr 01 153307
Why is the moon in a different place every night? (Beginner) Apr 01 252522
What happened to all the black holes that were around in the early universe? (Intermediate) Mar 01 49444
Why do some eclipses take longer than others? (Intermediate) Jan 01 56175
What is a star's "spectrum"? (Beginner) Oct 00 101884
How can we distinguish a star's "real" color from the change in color that we observe due to the star's motion? (Intermediate) Oct 00 64176

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