\documentclass{article}

\usepackage{amssymb,amsmath}
\usepackage{hyperref}
\usepackage{graphicx}
\usepackage{eso-pic}
\usepackage{epstopdf}
\usepackage{type1cm}
\usepackage[utf8x]{inputenc}

\newcommand{\TeXForWeb}{\TeX$^4$Web}
\newcommand{\cref}[2][\relax]{\href{http://sciencewise.info/ontology/#2}{\ifx#1\relax#2\else#1\fi}}
\newcommand{\dref}[2][\relax]{\href{http://sciencewise.info/definitions/#2}{\ifx#1\relax#2\else#1\fi}}
\newcommand{\fileref}[2][\relax]{\href{http://sciencewise.info//definitions/Astrometric_microlensing_by_Oleg_Ruchayskiy/#2}{\ifx#1\relax#2\else#1\fi}}

\title{Astrometric microlensing by Oleg Ruchayskiy}

\begin{document}

\maketitle

Change in the apparent position \emph{position} of a background \cref{star} when an object (lens) moves in front of it

\end{document}