Iain answers your astronomical questions: X, Y and Z

- Mark Leach has a question about neutron star deformation
- Phil Rushton asks about order in the Solar System
- Frances Cairns asks, "Is the Big Bang still happening?"

George answers your astronomical questions: Metalenses, photon directionality and the frequency of comet visitation

- Mark asks, "How will the new Metalens developments help astronomy?"
- John wants to know if photons have a preferred direction
- Eleanor asks "How often can we see comets?"

As the speed of light is such a critical factor in the search for ET, we rounded up all our questions related to c and gave them to Francesca Pearce. With Mateusz Malenta, she tackles questions from Ben Dyer, Henning Vester Jorgensen and Tom Perry who all have concerns about the nature and propagation of light, and time.

]]>Minnie, Ben and George answer your astronomical questions: Galaxy Collisions, telescopes and asteroids

- Alex asks, "What would happen if our galaxy collided with another?"
- Oliver asks us what kind of object are visible with telescopes
- Gillian wants to know about the ever-present dangers from space

Minnie, Ben, and George answer your astronomical questions:

- June asks: "What is a radio galaxy? (Bonus question: What do astronomers do all day?")
- Alexander asks: "When will Halley's comet be returning?"
- Assya asks: "How many astronomers are in space?"

Minnie, Ben and George answer your astronomical questions: The distance to the Sun, life on Mars and the number of stars in the Universe

- Emelia asks, "How far away is the Sun?"
- Natalie wants to know if there's life on Mars
- Joshua asks "How many stars are there in space?"

Dr Iain McDonald answers your astronomical questions: Metals in stars, the problem with information and Life on Mars

- YODATHEOAK asks about the production of metals in stars,
- Phillip Le Riche wants to know why cosmologists care about conservation of information
- Paul Stevenson asks, "Should we revisit the results from Mars' Viking Lander?"

Benjamin Shaw answers your astronomical questions: Disentagling redshift and demoted Neptune.

- Owen asks about the different sources of redshift and how we tell the difference between them
- Jacqeline wants to know why Neptune is still a planet when Pluto crosses its orbit

Dr Iain McDonald answers your astronomical questions: Science in The Martian, Jupiter's red spot and the fate of the Earth and Moon.

- Penny wants to know if Matt Damon could really propell himself around with his space suit
- Mark asks "When will Jupiter's great red spot disappear?"
- Charles wants to know what will happen to the Earth-Moon system when the Sun enters the Red Giant branch

Dr. Joe Zuntz answers your astronomical questions:

- li>Christoph Krahenbuhl asks: "Are the Gaia measurements affected by gravitational waves and how can that be compensated for accurately?"
- Paul Wagstaff asks: "Why is inflation necessary to explain isotropy? To my, untutored mind, a point universe similar in all respects should remain so regardless of the speed of expansion."
- Matthew Wilday asks: "We all know about time dilation understand the principal and even get the equation but my question is this: if we managed to build a space craft capable of going to 98% of the speed of light, what would the pilot see if we pointed him at a stat 100 light years away? We know the light would take 100 years, but the pilot would get there in (in his reference frame) less than 100 years, so would he see space shrink?

Prof. Tim O' Brien answers your astronomical questions:

- Christoph asks, "What single space mission would you launch in the next ten years if money was no constraint?"
- Russ asks about the perception of gravity on the International Space Station.
- @Malcontent (via Twitter) wants to know if the missing mass in the Universe could be hiding in black holes.

Dr Anna Scaife answers your astronomical questions:

- Christoph Krahenbuhl asks: "How do you deal with all the interference of electromagnetic waves around Jodrell Bank (I wonder every time I pass in a car or on a train)? Does it become worse over time? Will there come a time when it renders Jodrell Bank useless?"
- Paul Stevenson asks: "What is the best way for an amateur to get started with Radio Astronomy and are there any books or courses you would recommend?"
- Christoph Krahenbuhl asks: "What difference would putting telescope on the dark side of the moon make? Thinking in general but also about spotting inbound asteroids that threaten the earth."

David Ault, George Bendo, Jen Gupta, Ian Harrison, Chris Lintott, Stuart Lowe, Ian Morison and Mark Purver answer your astronomical questions:

- Eleanor Horner asks "What is the universe expanding into?"
- Chris Walker shows us a rather curious object he caught whilst taking images of The Pleiades
- Paul Stevenson wants to know what cause the orbital inclination of Hot Jupiters
- Tom Chiverton wonders whether a trip to Mars is worth retiring the ISS
- Ian Wilkinson asks "Is there a universal set of units that are extrinsic to the Solar System?"
- Stephen Roderick and Mark gray ask us what the recent discovery of gravitational waves means for astronomy

Dr Joe Zuntz answers your astronomical questions:

- Kenny Macleod asks us about cosmological redshift and what properties of the universe it affects
- Martin wants to know about the speed at which the unverse can expand and how could spacetime have behaved close to the Big Bang
- Philip King asks, "Can a gravitational lens reveal an object at different distances and times?"

Dr Iain McDonald answers your astronomical questions:

- Armando asks us about near Kuiper Belt misses by our long distance spacecraft
- Ian wonders about the curvature of the Earth
- Sean wants to know what the most distant object his eyes will allow him to see is

New Jodcaster Dr Anna Scaife answers your astronomical questions:

- Stanely Furtig asks us about the relativity corrections applied to the clocks on GPS satellites.
- Matthew Wilday wants to know about the number of stars that intercept our radio transmissions
- Russ Jenkins asks us about the interior of Mars

Dr George Bendo answers your astronomical questions:

- Simon Everitt asks: What effect does the Solar corona have on heating the Earth?
- Paul Stevenson asks: How do elliptical galaxies form from the mergers of spirals?
- Russ Jenkins asks: What temperature gradient would you measure, if you were to dig down to the centre of Mars?

Dr Joe Zuntz answers your astronomical questions:

- Phillip asks, "When normal matter falls into a black hole, a proportion of its mass is converted into energy, which is radiated in the electromagnetic spectrum. However, this would not be possible for a particle of dark matter as it can neither absorb nor radiate electromagnetic energy. So how would the energy escape? Does this imply that if there exists dark matter then there must also exist dark radiation of some form? Could this even be gravitational waves?"
- Ike asks: "I was taught that photons do not interact with one another, that is why you can cross laser beams. Now I learned that gamma rays interact with background photons to produce a electron-positron pair. What are the rules for interacting photons?"
- Robert asks: "Is the Sun's mass increased by the thermal motion of its atoms, following the mass-energy equivalence of special relativity? If so, how much?"

Dr Joe Zuntz answers your astronomical questions:

- John Brooks asks: "If you could increase a photon of light (in its particle form) to the size of our sun, what would its potential power output be?"
- The second question also comes from John Brooks: "Could missing dark matter be located beyond the "visible universe"?"
- Andrew Horner asks: "In a recent episode of Radio 4's In Our Time on dark matter, one of the contributors, Prof Carlos Frenk of Durham University, said that the cosmic microwave background unambiguously tells us how much ordinary baryonic matter there is in the universe. Can you explain how this is so?"