Which planet is closest to Earth ?

Forums Mars Which planet is closest to Earth ?

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    Mr Jack Martin

    A Sky at Night program said it was Mars.

    I invite others to say if they think it is or isn’t and if so why.

    Or is it Mercury or Venus instead ?

    I will post the answer this time next week.

    Regards to all,


    Essex UK
    Dr Andrew Smith

    I assume you mean now as the answer is time dependant.

    Regards Andrew 

    Steve Knight

    Think if you elminate time dependency, average distance, it’s Mercury.

    Closest at some time, Venus.


    Grant Privett

    Closest now or closest ever?

    David Swan

    Indeed there are different average measures.

    If you put all the days of a randomly chosen year in a hat, pull one out, and then have to guess which planet is closest to us on that day: Mercury would be the wisest choice.

    Yes, I listened to this section on the BBC’s More or Less


    Chris Dole

    Without cheating and looking it up, I’ve always thought that Venus is the closest most frequently, Mars occasionally and Mercury very infrequently. So overall I’d say Venus. I have a feeling that I may be mistaken though!

    Although it’s not really clear from the question whether it’s about time overall or specific occasions.

    Peter Mulligan

    The planet that can come the closest to the Earth is of course Venus around inferior conjunction when its around 25 million miles away. But Mars or Mercury could be closest to the Earth depending where Venus is on its orbit for example at superior conjunction.

    Mr Jack Martin

    On a long term average which of the 3 planets is most often closer to Earth ?

    As Steve and David have given the correct answer Mercury, it would be pointless leaving it till next week.

    Follow the link on David’s post for more a more detailed explanation.

    Well done everybody who responded.


    Essex UK 

    Jeremy Shears

    I listened to BBC Radio 4’s More or Less programme as I was driving home from Liverpool last Sunday evening. It’s one of my favourite radio programmes and the discussion on the “nearest planet” question was brilliant. It featured Prof David Rothery, who is a regular speaker at BAA meetings. Well worth a listen on iPlayer.

    David Swan

    Sorry for being a party pooper with the link, Jack. I think you have raised an interesting topic for discussion and I wanted to put here the link to the programme for anyone who is interested.

    There are several issues here aren’t there – for example about how one interprets a loose statement like ‘Mars, our nearest neighbour’ that was used on the Sky at Night. Of course, as people have pointed out, ‘which planet can get closest to Earth?’ is a quite different question to ‘which planet is most often the closest to Earth?’, and indeed ‘which planet is closest to Earth now (or indeed any specified time)?’.

    Revealingly, Chris Lintott, an accomplished astrophysicist, checked that Mars was closer than Venus at the time of broadcast, but didn’t even think to check the distance to Mercury at that time. I am not saying any of you are guilty of this, but I think we can probably say that many people will just think of the sequence of orbital ellipses around the sun and conclude ‘it must be either Venus or Mars, mustn’t it.’

    Also interesting is that (I hope I recall this correctly) the programme researchers looked through articles around this topic and found that there wasn’t anything published on this question. On something so simple, this is very interesting.

    P.S. I second Jeremy’s point about More or Less. I subscribe to the podcast.  I was hooting with laughter as Tim Harford took a nutritionist to task about the difference between ‘facts’ and what might be ‘good policy’ – relating to data on sugar consumption over time.

    Mr Jack Martin


    While we are all fallible, your right it depends on how the question is worded.

    When I was studying at the OU, this is something we had to understand and master, in order to get good scores on tutor marked assignments and exams.

    I agree its a very interesting question, which has only recently been researched and answered correctly.

    We have all learned something new !



    Essex UK

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