WordPress: get author info from post id

Question

Or even the author id from the post id. I am trying to return the author meta (author page link and avatar) in the sidebar of a single post page (outside of the post loop). What is the best way to do this? I am using a custom function (see below) to return the post id, but am not sure what function to call next.

function this_post_id() {
  global $wp_query;
  $thePostID = $wp_query->post->ID;
  return $thePostID;
}

Answer 1

I figured it out.

<?php $author_id=$post->post_author; ?>
<img src="<?php the_author_meta( 'avatar' , $author_id ); ?> " width="140" height="140" class="avatar" alt="<?php echo the_author_meta( 'display_name' , $author_id ); ?>" />
<?php the_author_meta( 'user_nicename' , $author_id ); ?>