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 48410
How long would it take the Earth to fall into the Sun? (Intermediate) Jul 05 116870
Have astronomers observed any phenomena that could be produced by extraterrestrial civilizations? (Intermediate) May 05 43949
Why are accretion disks flat? (Intermediate) Apr 05 48013
How do we know that nuclear fusion is still going on in the Sun? (Intermediate) Jan 05 72294
Is the universe really like an expanding balloon? (Intermediate) Jan 05 68995
If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths? (Intermediate) Dec 04 140818
How can we understand the meaning of large numbers like "a million million?" (Beginner) Nov 04 40611
Would extraterrestrial civilizations know that there is life on Earth? (Beginner) Oct 03 45301
Will the Moon be invisible in 500 million years? (Beginner) Oct 03 61430
What is apparent magnitude? (Intermediate) Sep 03 124867
Is the universe expanding faster than the speed of light? (Intermediate) Sep 03 455108
How do we define distance in an expanding universe? (Intermediate) Aug 03 78798
When the Sun converts mass to energy, do the orbits of the planets change? (Advanced) Aug 03 111881
What is the observational difference between a star and a planet? (Beginner) Jul 03 253463
How long do supernova remnants last? (Intermediate) May 03 47819
What is the universe expanding into? (Intermediate) Apr 03 561469
How can we see galaxies if their stars are so faint? (Intermediate) Feb 03 48559
Does gravity vary across the surface of the Earth? (Intermediate) Feb 03 232457
What process would bring about a quark star? (Intermediate) Jan 03 44595
Could there be life in the galaxies nearest to the Milky Way? (Intermediate) Jan 03 126829
Does evolution contradict the second law of thermodynamics? (Intermediate) Jan 03 189775
How does the brightness of a star depend on its distance from us? (Beginner) Dec 02 78169
How do astronauts communicate with their families from space? (Beginner) Dec 02 68623
Can you see the future as you fall into a black hole? (Intermediate) Dec 02 94349
How can we see the Milky Way if we are inside it? (Intermediate) Dec 02 351937
When we look back to the Big Bang, why don't we see the universe as a tiny speck of matter? (Intermediate) Dec 02 62208
Why do astronauts in space need to exercise? (Beginner) Nov 02 50975
Why doesn't the length of each day change much around the solstices? (Intermediate) Nov 02 89238
Do we see the same stars from above and below the equator? (Beginner) Nov 02 107174
Why isn't the sky bright at night if the universe has so many stars? (Intermediate) Nov 02 220807
What are "blue stragglers" in globular clusters? (Intermediate) Nov 02 66733
How do you calculate the lifetime of the Sun? (Advanced) Nov 02 164102
How long does a solar eclipse last? (Beginner) Oct 02 162487
What companies or businesses can astronomers work for? (Beginner) Oct 02 67891
Why aren't accretion disks around giant stars as hot as accretion disks around black holes? (Advanced) Oct 02 40022
What is the farthest in space that we have gone? (Beginner) Oct 02 108724
How close does a supernova need to be to damage the Earth's environment? (Intermediate) Sep 02 48617
Is light of different colors affected differently by gravity? (Intermediate) May 02 42004
Why do clocks turn in the opposite direction from the Earth and Moon? (Intermediate) Apr 02 80722
Do most astronomers believe in God based on the available scientific evidence? (Beginner) Mar 02 119804
What can we learn from the color of a star? (Intermediate) Mar 02 148382
What happens to a substance if its speed is more than the speed of light? (Intermediate) Mar 02 131136
Will we ever stop having solar eclipses because of the moon's motion away from the Earth? (Intermediate) Feb 02 90307
Could there have been multiple Big Bangs at different places in the universe? (Intermediate) Feb 02 62852
What is the difference between the "Doppler" redshift and the "gravitational" or "cosmological" redshift? (Advanced) Feb 02 87322
How do astronauts use math in their jobs? (Beginner) Feb 02 89852
How does astronomy benefit humankind? (Beginner) Dec 01 113653
What is the physical difference between a star and a planet? (Intermediate) Sep 01 351683
Could dark energy come from matter anti-matter pairs forming spontaneously and then annihilating? (Advanced) Aug 01 44666
Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background? (Advanced) Aug 01 38603
What does the term "visible universe" mean? (Beginner) Jul 01 50726
How do astronomers use math in their jobs? (Beginner) May 01 162418
What is the density of a black hole? (Advanced) Apr 01 132011
Why is the moon in a different place every night? (Beginner) Apr 01 202362
What happened to all the black holes that were around in the early universe? (Intermediate) Mar 01 43648
Why do some eclipses take longer than others? (Intermediate) Jan 01 48190
What is a star's "spectrum"? (Beginner) Oct 00 88417
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 55397

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