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 51703
How long would it take the Earth to fall into the Sun? (Intermediate) Jul 05 123794
Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (Intermediate) May 05 46272
Why are accretion disks flat? (Intermediate) Apr 05 50444
How do we know that nuclear fusion is still going on in the Sun? (Intermediate) Jan 05 76100
Is the universe really like an expanding balloon? (Intermediate) Jan 05 75186
If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (Intermediate) Dec 04 152653
How can we understand the meaning of large numbers like "a million million?" (Beginner) Nov 04 42502
Would extraterrestrial civilizations know that there is life on Earth? (Beginner) Oct 03 47311
Will the Moon be invisible in 500 million years? (Beginner) Oct 03 63983
What is apparent magnitude? (Intermediate) Sep 03 128010
Is the universe expanding faster than the speed of light? (Intermediate) Sep 03 475282
How do we define distance in an expanding universe? (Intermediate) Aug 03 84056
When the Sun converts mass to energy, do the orbits of the planets change? (Advanced) Aug 03 115741
What is the observational difference between a star and a planet? (Beginner) Jul 03 275142
How long do supernova remnants last? (Intermediate) May 03 50200
What is the universe expanding into? (Intermediate) Apr 03 586534
How can we see galaxies if their stars are so faint? (Intermediate) Feb 03 50524
Does gravity vary across the surface of the Earth? (Intermediate) Feb 03 246202
What process would bring about a quark star? (Intermediate) Jan 03 46490
Could there be life in the galaxies nearest to the Milky Way? (Intermediate) Jan 03 132549
Does evolution contradict the second law of thermodynamics? (Intermediate) Jan 03 198322
How does the brightness of a star depend on its distance from us? (Beginner) Dec 02 84370
How do astronauts communicate with their families from space? (Beginner) Dec 02 72797
Can you see the future as you fall into a black hole? (Intermediate) Dec 02 100916
How can we see the Milky Way if we are inside it? (Intermediate) Dec 02 364349
When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (Intermediate) Dec 02 64968
Why do astronauts in space need to exercise? (Beginner) Nov 02 52848
Why doesn't the length of each day change much around the solstices? (Intermediate) Nov 02 91803
Do we see the same stars from above and below the equator? (Beginner) Nov 02 118703
Why isn't the sky bright at night if the universe has so many stars? (Intermediate) Nov 02 226433
What are "blue stragglers" in globular clusters? (Intermediate) Nov 02 69488
How do you calculate the lifetime of the Sun? (Advanced) Nov 02 171021
How long does a solar eclipse last? (Beginner) Oct 02 165373
What companies or businesses can astronomers work for? (Beginner) Oct 02 71320
Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (Advanced) Oct 02 42448
What is the farthest in space that we have gone? (Beginner) Oct 02 122295
How close does a supernova need to be to damage the Earth's environment? (Intermediate) Sep 02 51017
Is light of different colors affected differently by gravity? (Intermediate) May 02 44497
Why do clocks turn in the opposite direction from the Earth and Moon? (Intermediate) Apr 02 85364
Do most astronomers believe in God based on the available scientific evidence? (Beginner) Mar 02 125798
What can we learn from the color of a star? (Intermediate) Mar 02 162733
What happens to a substance if its speed is more than the speed of light? (Intermediate) Mar 02 138881
Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (Intermediate) Feb 02 93216
Could there have been multiple Big Bangs at different places in the universe? (Intermediate) Feb 02 66782
What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (Advanced) Feb 02 93647
How do astronauts use math in their jobs? (Beginner) Feb 02 93340
How does astronomy benefit humankind? (Beginner) Dec 01 119989
What is the physical difference between a star and a planet? (Intermediate) Sep 01 373140
Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (Advanced) Aug 01 46637
Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (Advanced) Aug 01 40366
What does the term "visible universe" mean? (Beginner) Jul 01 53146
How do astronomers use math in their jobs? (Beginner) May 01 169778
What is the density of a black hole? (Advanced) Apr 01 138874
Why is the moon in a different place every night? (Beginner) Apr 01 217289
What happened to all the black holes that were around in the early universe? (Intermediate) Mar 01 45480
Why do some eclipses take longer than others? (Intermediate) Jan 01 50529
What is a star's "spectrum"? (Beginner) Oct 00 92668
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 58120

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